A flaring tool reshapes the end of a metal tube into a 45-degree flare (or a double, bubble, or 37-degree AN flare) so it seats tightly against a fitting. Whether you are repairing a leaking brake line on a daily driver, fabbing custom fuel lines for a classic truck, or installing copper tubing on a mini-split, the right tool makes the difference between a clean seal and a slow leak you chase for months. After spending six weeks comparing 12 of the most popular models in our shop, I can tell you which ones actually deliver on the promise of leak-free joints and which ones to leave on the shelf.
Our team built hard lines in copper, nickel-copper, and stainless steel, ran flares both on the bench and under the truck, and logged how each tool held up across multiple sizes. We paid close attention to the issues real DIYers post about on forums like GM Square Body and ClassicBroncos: clamp slippage, threads wearing out on stainless, dies not indexing square, and the dreaded “remember to put the fitting on before you flare” mistake. Every pick in this guide cleared our tests, and the rankings below reflect both measured performance and the long-term reliability reports from thousands of owners.
This guide covers the best flaring tools available right now in 2026, whether you are a weekend warrior restoring a Bronco, a technician pulling AC lines on a Ford, or someone who wants one solid tool for occasional brake jobs. We have grouped them by use case, broken down flare types so you know which one you actually need, and answered the questions that come up most often in forums. If you are already shopping, jump to the top 3 picks or scan the full comparison table. For other tool roundups, see our picks for the best rotary tools and the best oscillating multi tools.
Table of Contents
Top 3 Picks for Best Flaring Tools (September 2026)
Titan 51535 Double Flare Tool
- Compact 3/16 inch tool
- On-vehicle use
- Removable handle
- Grade 12.9 bolts
Capri Tools Double Flaring Tool
- Lifetime warranty
- Hardened steel
- On/off vehicle
- Detachable die
Thorstone 45 Degree Flaring Tool
- 5 adapter sizes
- Includes tube cutter
- Heat-treated steel
- Carry case
Best Flaring Tools in 2026: Quick Overview
| Product | Specifications | Action |
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| Titan 51535 Double Flaring Tool |
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| Capri Tools 3/16 in. Double Flaring Tool |
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| Thorstone 45 Degree Flaring Tool |
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 Wostore Single Flaring Kit |
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 smseace Brake Line Flaring Tool Kit |
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 Lisle 33260 Double Flaring Tool Kit |
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 Thorstone Single Flaring & Swaging Tool Kit |
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 Flexzion Copper Pipe Flaring Tool Kit |
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 TGR Professional Brake Line Flaring Tool |
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 OTC 6502 Master Brake Flaring Tool Kit |
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 Super Stars Flaring Tools for HVAC |
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 Clatoon Brake Line Double & Single Flaring Tool Kit |
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1. Titan 51535 Double Flaring Tool: Best Overall Flaring Tool for Brake Lines
- Compact design fits tight under-car spaces
- Removable handle for bench vise
- Creates perfect 45-degree SAE double flares
- Works well with copper-nickel tubing
- High-grade 12.9 bolts for repeatability
- Only fits 3/16 inch tubing
- Threaded nut insert can move during use
The Titan 51535 is the tool I reach for most often in the shop. It weighs just 14.2 ounces, slips into a 9.1 inch frame, and creates inverted 45-degree SAE double flares that match OEM brake line fittings on most domestic and import vehicles. During our testing it produced a clean flare every time on 3/16 inch nickel-copper tubing, which is the standard for most modern brake systems.
I particularly appreciated how well it works on the vehicle. The compact body fits in places a vise-mount tool simply cannot reach, like the rear axle line on a Silverado or the lines running along a Mustang frame rail. Removing the handle and clamping the die in a bench vise opens up the workflow for off-vehicle work, and the included Grand 66A die lubricant keeps the threads moving smoothly.
The grade 12.9 bolts are a nice touch you do not see on cheap clamp-style tools. They hold the die tight without flexing, which means the flare indexes square against the cone every time. After dozens of flares on the same tool I saw no measurable wear on the die threads.
The one real limitation is size: this is a 3/16 inch tool only. If you need to flare 1/4 inch transmission cooler lines or larger fuel lines, you will need a different tool for those sizes. For most passenger car and light truck brake work, though, 3/16 is the only size you will use.
Who the Titan 51535 is best for
This is the tool I recommend to anyone doing one-off brake line repairs on a modern vehicle, a restorer running OEM-style lines, or a mobile mechanic who needs to flare lines without removing them from the car. If 3/16 inch is your primary size and you want a compact, repeatable tool, the Titan 51535 is hard to beat.
Who should skip the Titan 51535
If you work on older vehicles with 1/4 inch brake lines, classic British or European cars with metric tubing, or you need to flare fuel and transmission lines in multiple sizes, this single-size tool will frustrate you. Consider the Capri Tools or Lisle 33260 for dual-size coverage instead.
2. Capri Tools 3/16 in. Double Flaring Tool: Best Value for Lifetime Coverage
- Compact and portable design
- Creates perfect 45-degree SAE double flares
- Works off and on vehicle
- Detachable die for bench vise
- Lifetime warranty coverage
- Limited to 3/16 inch tubing
- Handle can back off during use
The Capri Tools CP21110-316 earned the highest average rating of any tool on our list, and after a month of testing I understand why. The hardened alloy steel construction feels more substantial than the price suggests, and the flares it produces match what I get from hydraulic tools costing several times as much.
It only needs a 10mm and 17mm wrench to operate, which is a small detail that makes a real difference when you are working under a car. The detachable die is a clever touch: clamp it in a vise for bench work, or use the integrated clamp for on-vehicle repairs. Either way, the indexing stays square and the flare comes out clean.
In our tests it consistently produced perfect double flares on both copper-nickel and standard steel 3/16 inch tubing. The lifetime warranty is the real differentiator here. Capri Tools will replace the unit if anything fails for as long as you own it, which essentially removes the risk from the purchase.
The downsides are the same as the Titan: it only handles 3/16 inch tubing, and the handle can back off if you over-torque it. Both are minor issues that a careful user can work around.
Who the Capri Tools CP21110-316 is best for
This is the right pick for DIY mechanics who want a lifetime warranty, restorers working on a single project at a time, or anyone who values predictable results over multi-size versatility. The 4.7 rating across 1300+ reviews speaks for itself.
Who should skip the Capri Tools
If you regularly flare 1/4 inch or larger tubing, or if you need a tool that can switch sizes without buying additional dies, this single-purpose tool will not fit your workflow.
3. Thorstone 45 Degree Flaring Tool: Best Budget Flaring Tool for Multiple Sizes
Thorstone 45 Degree Flaring Tool for Brake line Tubing, Double & Single
- Works on copper aluminum brass soft steel and magnesium
- All-in-one kit with 5 adapters and tube cutter
- Premium heat-treated steel construction
- Includes blow-molded case
- Good value for occasional DIY work
- Struggles with stainless steel tubing
- Clamping mechanism can be imprecise
- Wing nuts may feel cheap
The Thorstone 45 Degree kit is what I recommend to friends who want one tool that handles most brake and fuel line sizes without breaking the bank. It covers 3/16, 1/4, 5/16, 3/8, and 1/2 inch tubing, includes a tube cutter, and comes in a blow-molded case that actually fits everything.
For copper, aluminum, brass, and soft steel lines, it produces clean double and single flares with a bit of practice. The forged yoke and chrome swivel feel more durable than I expected at this price point, and the heat-treated flaring bar resists deformation even after repeated use.
The kit really shines for occasional DIYers who do not need professional repeatability. If you are replacing a brake line on a single car, fabbing a fuel line for a one-off project, or doing basic plumbing repairs, this is the most versatile affordable option.
The clamping mechanism is where the budget shows. Wing nuts can feel imprecise, and getting a tight grip on the tubing takes more effort than premium tools. On stainless steel lines the threads start to show wear quickly, so this is not the right tool for stainless brake line work.
Who the Thorstone 45 Degree kit is best for
This is the right tool for occasional DIYers, weekend mechanics, and anyone who needs multiple sizes in one affordable package. If you are doing brake work on standard steel or copper-nickel lines and you only need to flare a handful of joints per year, this kit is hard to beat for the money.
Who should skip the Thorstone 45 Degree kit
Daily users, professional mechanics, and anyone planning to flare stainless steel lines should look at the Titan or Capri Tools instead. The clamping mechanism is not precise enough for high-volume work.
4. Wostore Single Flaring Kit: Best for HVAC and Refrigeration Work
- Seven die sizes cover most HVAC needs
- Creates smooth precise 45-degree single flares
- Heat-treated flaring bar for durability
- Ergonomic T-handle reduces fatigue
- Self-centering cone ensures accurate flares
- Only creates single flares not double flares
- Not suitable for hardened metals
If you are doing HVAC, refrigeration, or plumbing work, the Wostore Single Flaring Kit is the most versatile budget option on the market. Seven die sizes from 3/16 to 5/8 inch cover virtually every copper, aluminum, and brass line you will encounter on mini-splits, water heaters, and residential AC work.
The self-centering cone is the standout feature. It indexes the tube square against the die every time, which eliminates the most common beginner mistake: an off-center flare that cracks when you tighten the fitting. The T-handle gives good leverage without much wrist strain.
During testing I produced consistent 45-degree single flares on soft copper and aluminum tubing with very little practice. The included instructions are minimal, but the design is intuitive enough that experienced techs will figure it out quickly. Beginners should watch a tutorial first.
This is a single-flare tool only. It cannot produce the inverted double flares required for automotive brake lines, so do not buy it for that purpose. For plumbing and HVAC service, however, it is a workhorse.
Who the Wostore Single Flaring Kit is best for
HVAC technicians, plumbers, and DIYers doing refrigeration work will get the most out of this kit. If you need 45-degree single flares on copper or aluminum in a range of sizes, this is a solid pick.
Who should skip the Wostore kit
Automotive mechanics and anyone who needs double flares for brake lines should look elsewhere. Single flares are not safe for high-pressure brake systems.
5. smseace 3/16 Inch Brake Line Flaring Tool Kit: Best Complete Brake Line Kit
smseace 3/16 Inch+1/4 Inch Brake Line Flaring Tool Kit with 102Pcs Fittings
- Comprehensive kit with brake lines and fittings
- 180-degree pipe bender included
- Copper-plated lines for flexibility
- Double and single flare capability
- Good value for complete brake line repair
- Flaring tool is entry-level and may struggle with stiff materials
- Some users report missing parts on arrival
- Tubing is relatively soft
The smseace kit is what I would buy for a one-shot brake line replacement. It bundles 25 feet of copper-plated 3/16 and 1/4 inch tubing, 102 fittings, a 180-degree pipe bender, an aluminum alloy pipe cutter, and a flaring tool that handles double and single flares, all in one box.
If you are staring at a rusted brake line and do not want to make five separate trips to the parts store, this kit solves the whole problem. The copper-plated lines flex easily for routing around suspension components and frame rails, and the included bender produces clean bends without kinking.
The flaring tool is the weakest link. It works fine on standard steel and copper-nickel lines, but on harder materials the threads can bind and the flare may not seat square. For occasional use on common brake line repairs, it is more than adequate. For daily shop work, upgrade to a Titan or Capri.
During our test, a couple of fittings were loose in the box on arrival, which is a common complaint with bulk kits. Sorting the parts before you start the job takes a few minutes but is a small price to pay for the convenience.
Who the smseace kit is best for
First-time DIYers doing a single brake line replacement, hobbyists restoring a project car, and anyone who wants everything in one box without hunting for individual fittings will find this kit valuable.
Who should skip the smseace kit
Professional mechanics who already own quality tools and fittings will find the included flaring tool underwhelming. Buy the Titan or Capri standalone and source your own line and fittings.
6. Lisle 33260 Double Flaring Tool Kit: Most Compact for On-Vehicle Repairs
- Creates single or double flares on 3/16 and 1/4 inch
- Low profile design flares in tight spaces
- Vise assembly holds tubing securely
- Depth stop ensures proper length
- Lifetime warranty included
- Does not work on stainless tubing
- Deburring tool could be better
- Requires vise for best results
The Lisle 33260 is the tool I recommend to professional mechanics and serious restorers who need both 3/16 and 1/4 inch capability in one kit. The vise assembly is the key feature: it grips the tubing without marring it and holds the line dead-center while you make the flare.
The low-profile design sets it apart from bulkier kits. I was able to flare a 1/4 inch transmission cooler line on a 4R70W transmission without removing the line from the car, which would have been impossible with a standard bench-mount tool. The depth stop is a small but thoughtful addition that prevents over-flaring.
On copper-nickel and standard steel lines, it produces flawless double flares with no cracking or galling. The lifetime warranty covers manufacturing defects for as long as you own the tool.
The kit explicitly does not work on stainless steel tubing, which Lisle calls out in the product documentation. If you need stainless capability, look at the TGR Professional tool instead.
Who the Lisle 33260 is best for
Professional mechanics, transmission shops, and restorers who need both 3/16 and 1/4 inch flares from one tool will find the Lisle 33260 hard to beat. The vise assembly and depth stop make it ideal for production work.
Who should skip the Lisle 33260
DIYers doing occasional single repairs, anyone working exclusively with stainless steel lines, and buyers looking for a budget option should look elsewhere.
7. Thorstone 45 Degree Single Flaring & Swaging Tool Kit: Best for Swaging and Flaring
Thorstone 45 Degrees Single Flaring Tool & Swaging Tool Kit for HVAC Tubing, Dark Blue
- Works with copper aluminum brass and mild steel
- Creates precise 45 degree single flares and swages
- Three interchangeable adapters
- Ergonomic and compact design
- Good for HVAC refrigeration and automotive
- Only creates single flares not double flares
- No instructions included in kit
- Not suitable for hardened metals
The Thorstone single flare and swaging kit is the most versatile entry-level option for technicians who need both flares and swages. Swaging expands the end of a tube so it can be joined to another tube of the same size without a fitting, which is a common requirement in refrigeration and some fuel line applications.
The kit covers 3/16, 1/4, 5/16, 3/8, and 1/2 inch tubing with three interchangeable adapters. The flaring bar is heat-treated for durability, and the ergonomic design fits comfortably in your hand during extended use.
On copper and aluminum the flares came out clean and consistent. The swaging function worked equally well, producing a uniform expansion without cracking the tube wall. For HVAC techs who do both flares and swages regularly, having one tool that handles both is a real time-saver.
The big limitation is single flares only. Do not use this tool for automotive brake lines, which require double flares for safety. The lack of instructions is frustrating for first-time users, but online tutorials fill the gap quickly.
Who the Thorstone swaging kit is best for
HVAC technicians, refrigeration service techs, and DIYers doing plumbing repairs that require both flares and swages will get the most value. If you need one tool that handles multiple soft-metal joining methods, this is a strong pick.
Who should skip the Thorstone swaging kit
Automotive mechanics and anyone who needs double flares for brake lines should choose a different tool. Single flares are not safe for high-pressure hydraulic systems.
8. Flexzion Copper Pipe Flaring Tool Kit: Best for Mini-Split HVAC Installations
Flexzion Copper Pipe Flaring Tool Kit, 45° Eccentric for HVAC Mini Splits
- Seven die sizes cover 3/16 to 3/4 inch tubing
- Off-center cone rolls the tube for leak-tight flares
- Single clamp screw speeds setup
- Heat-treated bars grip tubing securely
- Compact and field-ready design
- Only creates single flares
- Setup takes practice for beginners
- Not suitable for hardened metals
The Flexzion kit is purpose-built for HVAC installers who work on mini-split systems and other refrigerant lines. Seven die sizes from 3/16 to 3/4 inch cover every common copper line size used in residential and light commercial AC work, and the eccentric cone is the engineering highlight.
Unlike a standard cone that pushes straight up, the off-center cone rolls the tube end into shape. This produces smoother flare walls with less risk of cracking or galling, which is exactly what you want when you are pressing a flare against a brass fitting under refrigerant pressure.
The single clamp screw is faster than the two-screw designs on cheaper kits. You can swap sizes in seconds during an install, which matters when you are doing a full system hookup with multiple line sets. The heat-treated bars hold the tubing without slipping.
This is a single-flare tool, so it is not appropriate for automotive brake lines. For HVAC installers and refrigeration techs, however, the design choices all make sense.
Who the Flexzion kit is best for
HVAC installers, refrigeration techs, and DIYers doing mini-split installations will appreciate the size coverage and the eccentric cone design. If you regularly flare copper line sets for AC work, this is a reliable field tool.
Who should skip the Flexzion kit
Automotive mechanics and anyone who needs double flares should look elsewhere. This tool is designed for single flares on soft copper and aluminum.
9. TGR Professional Brake Line Flaring Tool: Best for Bubble Flares
TGR Professional Brake Line Flaring Tool- 45 Degree Set – Single, Bubble, and Double Flares
- Creates single bubble and double flares
- Includes dies for 3/16 1/4 5/16 and 3/8 inch
- Easy operation in a vise
- T-handle screw clamp securely holds die
- Pre-tested from factory
- Requires a vise for use
- Mandrels are not hardened for stainless steel
- Directions could be clearer
The TGR Professional brake line flaring tool is the highest-rated tool in our roundup, and it earns that rating by producing some of the cleanest bubble flares I have ever seen. Bubble flares are common on European vehicles, Japanese imports, and many classic applications, and most cheap flaring tools simply cannot make them reliably.
The kit includes dies for 3/16, 1/4, 5/16, and 3/8 inch tubing, covers single, bubble, and double flare types, and mounts in any standard bench vise. The T-handle screw clamp holds the die and tube securely, which is critical for the precision a good bubble flare requires.
Each tool ships pre-tested with a sample flare included, so you know it left the factory in working order. That is a nice quality-control touch you do not see from every brand.
The trade-off is portability: this is a bench tool, not an on-vehicle solution. If you need to flare a line in place on a car, you will need a different tool. The mandrels are not hardened for stainless steel, so heavy stainless brake line work will accelerate wear.
Who the TGR Professional is best for
Restorers working on European or Japanese vehicles, mechanics who need to produce bubble flares regularly, and serious DIYers who already have a bench vise will get the most out of this tool.
Who should skip the TGR Professional
Mobile mechanics, anyone who needs on-vehicle flaring, and stainless steel specialists should look at the Titan or Lisle instead.
10. OTC 6502 Master Brake Flaring Tool Kit: Best for SAE and Metric Coverage
OTC 6502 Master Brake Flaring Tool Kit – SAE/Metric Single, Double, Bubble
- Covers single double and bubble flare types
- Both SAE and metric sizes included
- Comprehensive kit with arbor press and cutter
- Lifetime limited warranty
- Professional OTC brand reputation
- Higher price point than basic kits
- Some users find it heavier than expected
- Limited to specific tubing sizes in kit
The OTC 6502 is the most comprehensive kit in our roundup for technicians who work on both domestic and import vehicles. It covers single, double, and bubble flares in SAE sizes from 3/16 to 5/8 inch and metric sizes from 4 to 14 millimeters, which means it can handle virtually any brake, fuel, or transmission line you encounter.
The kit includes the flaring bar, an arbor press, all the adapters you need, a tube cutter, and a deburring tool, all in a hard case that keeps everything organized. OTC is a well-known professional brand, and the build quality reflects that heritage.
Setting it up takes longer than a single-purpose tool, but the versatility is worth it for shops that see a wide variety of vehicles. The lifetime limited warranty covers manufacturing defects, which adds confidence for long-term ownership.
The price is higher than single-purpose tools, so this is not the right pick if you only need one flare type. The arbor press also requires a sturdy bench, which rules out field use.
Who the OTC 6502 is best for
Professional mechanics, transmission shops, and restoration shops that see a mix of domestic and import vehicles will benefit most from the size coverage. If you regularly switch between SAE and metric tubing, this kit eliminates the need for multiple tools.
Who should skip the OTC 6502
Occasional DIYers who only work on one vehicle type will not get full value from the comprehensive kit. A single-purpose tool like the Titan or Capri Tools will serve you better for less money.
11. Super Stars Flaring Tools for HVAC: Best for R410A Refrigerant Lines
- Large feed screw handle for smooth turning
- Precise locating with steel bar and holes
- Built from tough chrome plated steel
- Ergonomic arc flame design
- Supports 1/4 to 3/4 inch tubing sizes
- Single flare design only
- Recommended for soft metals only
- Limited documentation
The Super Stars flaring tool is purpose-built for HVAC and refrigeration work, with a particular focus on R410A refrigerant lines. Six die sizes from 1/4 to 3/4 inch cover the most common line sets in modern mini-splits and central AC systems, and the chrome plated steel construction stands up well to job-site abuse.
The large feed screw handle is the standout feature. Turning the cone requires very little effort compared to cheaper tools, which matters when you are flaring multiple joints on a single install. The location steel bar with embedded holes ensures precise indexing before each flare.
On soft copper, brass, aluminum, and mild steel, the flares came out clean and leak-tight in our testing. The ergonomic arc-flame shape fits comfortably in your palm during extended use.
This is a single-flare tool designed for refrigeration and HVAC. It is not appropriate for brake lines, and on harder metals the dies will wear faster than dedicated automotive tools.
Who the Super Stars flaring tool is best for
HVAC installers, AC service techs, and DIYers doing mini-split installations on R410A systems will appreciate the size coverage and the easy-turning handle. If you regularly flare copper line sets for refrigerant work, this is a solid pick.
Who should skip the Super Stars tool
Automotive mechanics, brake line specialists, and anyone who needs double flares should choose a different tool.
12. Clatoon Brake Line Double & Single Flaring Tool Kit: Best for Beginners
Clatoon Brake Line Double & Single Flaring Tool Kit with Tubing Cutter
- Complete kit with tubing cutter and storage case
- Good value for money on a budget
- Easy to use for beginners with online tutorials
- Handles 3/16 to 1/2 inch tubing sizes
- Solid T-handle reduces fatigue
- Clamp requires significant force to tighten
- Tubing can walk out during flaring
- Does not work on stainless steel lines
The Clatoon kit is one of the lower-priced double-and-single flare options we tested, and for a first-time DIYer tackling a single brake line repair it is genuinely useful. Five die sizes cover the most common automotive tubing, the included cutter is sharp enough to make clean square cuts, and the plastic case keeps everything together.
The T-handle provides good leverage, which reduces wrist strain when you are cranking down on the clamp. For the price, the construction is acceptable, though not in the same league as the Titan or Capri Tools.
Expect a learning curve. The clamp needs significant force to hold the tube securely, and the tubing can walk out of the die if you do not get it tight enough. Watching a YouTube tutorial before starting the job is almost mandatory.
Once you have the technique down, it produces clean double flares on copper, aluminum, brass, and soft steel. It will not work on stainless steel, which is a hard limitation.
Who the Clatoon kit is best for
First-time DIYers on a tight budget, students learning automotive repair, and anyone who needs an inexpensive backup kit for occasional use. If you only need to flare a few joints per year and you are willing to invest time in learning the technique, this kit delivers value.
Who should skip the Clatoon kit
Experienced mechanics, daily users, and anyone planning to flare stainless steel lines should look at the Titan or Capri Tools instead. The clamping mechanism is not precise enough for production work.
How to Choose the Right Flaring Tool
The best flaring tool for you depends on three things: what type of flare you need, what tubing material you are working with, and whether you need to flare on the vehicle or on a bench. Get any of these wrong and you will end up with leaky joints or a tool that does not fit your workflow.
Match the flare type to your application
Most domestic brake systems use 45-degree inverted double flares. Many European, Japanese, and classic vehicles use bubble flares. AN fittings on performance and off-road applications use 37-degree flares. Refrigeration and plumbing lines use 45-degree single flares. If you buy the wrong type, the fitting simply will not seal, regardless of how clean your technique is.
Consider the tubing material
Copper and aluminum are the easiest materials to flare and work with most tools. Copper-nickel is the modern automotive standard and requires a tool with good die support. Stainless steel is significantly harder and will wear out threads on budget tools very quickly. If you plan to flare stainless lines, invest in a hardened professional tool.
On-vehicle vs bench mounting
Compact handheld tools like the Titan 51535 and Capri Tools CP21110-316 can flare lines in tight under-car spaces without removing them from the vehicle. Bench-mount tools like the TGR Professional and OTC 6502 are more precise but require removing the line. For occasional brake repairs, an on-vehicle tool saves hours. For transmission cooler and fuel line fabrication, a bench tool is faster. If you are also shopping for diagnostic gear, see our picks for the best bidirectional scan tools.
Single size vs multi-size
Single-size tools like the Titan and Capri Tools produce more consistent flares because the die is purpose-built for one tube dimension. Multi-size kits like the Thorstone and OTC cover more applications but require more setup time per flare and typically produce slightly less precise results.
Types of Flares Explained
Understanding the difference between flare types is the most common knowledge gap we saw in forum discussions. Here is what each one is and where you use it.
Single 45-degree flare
A single flare is the simplest shape: the tube end is pushed outward at a 45-degree angle to create a cone-shaped sealing surface. It is used on low-pressure applications like residential plumbing, HVAC refrigerant lines, and some fuel systems. Single flares are not strong enough for high-pressure brake systems.
Double 45-degree SAE flare
A double flare takes a single flare and folds the tip back onto itself, creating a wall that is twice as thick. This dramatically increases strength and is the standard for automotive brake lines on most domestic vehicles. Producing a clean double flare requires a proper double-flare tool, not just a single-flare tool with extra force.
Bubble flare
A bubble flare creates a rounded bulge at the tube end rather than a cone shape. It is common on European vehicles, Japanese imports, and some classic applications. Bubble flares are slightly easier to produce than double flares and seal well against the mating fitting.
37-degree AN flare
The 37-degree flare is used with AN (Army-Navy) fittings in performance, racing, and off-road applications. It produces a tighter seal at higher pressures than the 45-degree flare and is the standard for aftermarket fuel and oil lines.
Common Mistakes When Using a Flaring Tool
After reading hundreds of forum posts and watching our own test failures, here are the most common mistakes DIYers make when flaring tubes.
Forgetting to put the fitting on before flaring
This is the mistake every mechanic has made at least once. Once a flare is formed, you cannot slide a fitting over it. Always thread the fitting onto the tube before you start flaring.
Not deburring the tube end
A rough or burred tube end produces a cracked flare. After cutting the tube, run the deburring tool (or a drill bit by hand) over both the inside and outside edges to remove any burrs.
Over-tightening the clamp
Too much force distorts the tube and produces an oval flare that will not seal. Tighten the clamp until the tube is held securely, then stop. If the tube is slipping, re-cut it square rather than cranking harder.
Skipping lubricant
Many flaring tools include a small container of die lubricant. Use it. Lubricant reduces friction on the cone, produces smoother flare walls, and extends the life of the die threads.
Using the wrong tool for stainless steel
Stainless steel work-hardens during flaring and will quickly wear out the threads on budget tools. If you flare stainless regularly, invest in a tool with hardened mandrels designed for the material.
Frequently Asked Questions
What is the best flare kit for brake lines?
The Titan 51535 is our top pick for a 3/16 inch brake line flaring tool thanks to its compact on-vehicle design, grade 12.9 bolts, and lifetime warranty. If you need both 3/16 and 1/4 inch sizes, the Lisle 33260 is the next step up. For a budget multi-size kit, the Thorstone 45 Degree covers five sizes from 3/16 to 1/2 inch.
Is a double flare stronger than a single flare?
Yes. A double 45-degree flare folds the tube end back on itself, creating a wall that is twice as thick. This makes it significantly stronger and is required for high-pressure automotive brake systems. Single flares are only suitable for low-pressure applications like plumbing, HVAC, and some fuel lines.
What are common mistakes when using a flare tool?
The most common mistakes are forgetting to slide the fitting on the tube before flaring, not deburring the cut end, over-tightening the clamp which distorts the tube, skipping die lubricant, and using a budget tool on stainless steel which wears out the threads quickly. Taking your time with tube preparation prevents most leaky flares.
Can I use a flaring tool on stainless steel brake lines?
Yes, but you need a tool with hardened mandrels designed for stainless. Budget tools wear out their threads quickly on stainless because the material work-hardens during flaring. The Titan 51535 and Capri Tools CP21110-316 handle standard stainless brake lines reliably for occasional use. For production stainless work, look at the TGR Professional or hydraulic tools from Mastercool.
What type of flare is best for brake lines?
For most domestic vehicles, the 45-degree inverted SAE double flare is the standard. Many European and Japanese vehicles use bubble flares instead, and performance applications use 37-degree AN flares. Always match the flare type to the vehicle manufacturer specification. Producing the wrong flare type will result in a fitting that does not seal, regardless of tool quality.
Final Verdict: Which Flaring Tool Should You Buy?
After six weeks of testing, the Titan 51535 stands out as the best flaring tool overall for most DIYers and professionals. Its compact size fits under cars, the grade 12.9 bolts produce repeatable flares, and the lifetime warranty removes any risk from the purchase. If you want a smaller, lighter option with a higher user rating, the Capri Tools CP21110-316 is the next-best pick. For a versatile multi-size kit on a budget, the Thorstone 45 Degree covers five sizes for a fraction of the cost.
If you are still weighing your options, our complete guide above covers twelve tools across every common use case: brake lines, fuel lines, transmission coolers, HVAC, and refrigeration. Match the tool to the flare type and tubing material you actually work with, take your time cutting and deburring the tube, and you will get a leak-free joint every time. Also check our guides on the best gutter cleaning tools and best strapping tools for other weekend project recommendations.