What Size Brake Line Do I Need?

There is a standard-sized brake line used in almost every vehicle. Even so, many people ask: what size brake line do I need? You need this information to install a new one in case the original collapses. How would you do it? Let’s find out.

Life doesn’t come with a guarantee, and neither does your car. So, it is important to keep all the components of your vehicle smooth and working.

Talking about the components,  the brake line seems to be quite of some significance. The brake line is designed to keep your car safe from collision or an unfortunate accident, for those who do not know. 

When you push the brake pedal, the brake line allows the brake fluid to flow from the master cylinder to brake calipers to slow or stop the vehicle. So, this is how your vehicle is protected from colliding with another vehicle, a wall, or any other obstacle while you are driving on the road. 

However, brake lines can sometimes collapse themselves and demand repair due to an accident. During this time, we need to know the size of the brake line to install in the car. So, what size brake line would you need?  Do not worry because this article will help you figure out the same. Read on!

What Size Brake Line Do I Need

What Are Brake Lines?

Brake lines are fundamentally important for the safety of your vehicle, and their purpose is to save you from collision while you are driving. Thus, they should be checked regularly to ensure they are working reliably. 

Brake lines allow the brake fluid stored in the master cylinder to transfer into brake calipers to push the brake and bring the vehicle to a halt. This is why brake lines are a significant feature of the hydraulic brake system in a car. 


You might like to read: Why Are Brake Lines Coiled At The Master Cylinder


What Size Are Brake Line Fittings?

3/16″/4.75mm and 1/4″ are two of the most common brake line fittings, also known as flare fittings or tube nuts. Most cars and light SUVs/CUVs use a 3/16″ diameter brake line or flare fitting. The 3/16 inch brake line is most commonly used amongst the vehicles and is often called CNF-3. 

The ¼ inch was used in old times, around the 1950s. So, if your truck or vehicle was manufactured at that time and is still going, the chances are that you would need these brake line fittings. Vehicles that have been manufactured during recent years need 3/16 inch fittings. 

What Size Brake Line Do I Need?

Most manufacturers use either 3/16 inch brake line fittings these days. If not 3/16, they use the ¼ inch fittings. However, the actual size of the brake line can only be determined by the manufactured hydraulic system of the car. 

However, if you have to install custom brakes and cannot determine the size of the brake line fittings, try measuring it in the following steps. 

  • Consult the owner’s manual. It will help you learn about the exact location of the master cylinder and brake lines. 
  • Use a caliper to clamp that part of the brake, which you can easily find access to and rotate the dial. Remember to keep rotating the dial until the jaws are tight around the line.
  • Now, read the measurement recorded on the caliper. It must be recorded in inches or millimeters, sometimes both. 

What Size Brake Line Do I Need


Once the above steps are complete, you will have to use a standard or metric measurement method to find your vehicle’s right brake line size. There are two ways of measuring the brake line – via millimeters or inches. 

If you want to convert inches into millimeters, you must multiply it by 25.4 to get to the exact size. If you choose to convert millimeters into inches, divide the measurement by 25.4, and you will have the exact size of your brake line.

If you are new to the process, it is recommended to get some guidance from an expert or a friend who already has some experience. It is suggested because the size of the brake line will determine the safety of your vehicle. So, the measurement shouldn’t be lousy or incorrect.


You might like to read: What Happens If You Hold The Brake And Gas? Why Do Racers Do It, And Should You Do It Too?


What Size Brake Line for 2000 Silverado?

For 2000 Silverado, the typical size brake line is either 3/16 inch or ¼ inch. In the case of the customized brake system, you will have to measure the same with the help of a caliper. 

You can refer to the above paragraph for learning how to measure the brake lines. You can also get some guidance from an expert or get it done by a professional. 

Why Do Brake Lines Have Coils?

Brake lines have coils around them to prevent them from breaking due to fatigue that may or may not happen because of the constant movement in the brake system. The components of a brake system lead to regular movement or vibration. 

When the driver steps on the brake pedal, the brake system flexes, which allows the movement of the master cylinder but stops the vibration of other components in the system. 

If there are no coils on brake lines, there will be continued flexing and movement between the brake lines, causing fatigue in the lines and resulting in breakage (due to the vehicle’s motion).

Thus, having coils around the brake lines is quite important for the movement of the vehicle and its halting. 

What Size Brake Line Do I Need

People also ask 

#1. What is the standard size brake line?

The common size brake line is either 3/16 inch (which is the smaller size) or ¼ inch (, the larger size). The smaller size is also referred to as CNF-3, and the larger size has come to be known as CNF-4. 

Most vehicles have either of the above two brake lines in their brake system. Usually, 3/16 inches is considered to be the standard size brake line. 

#2. What size brake line should I use for rear disc brakes?

Disc brakes require high pressure to function, so they use a 3/16 inch or CNF-3 size brake line. On the other hand, drum brakes require less pressure but more volume to work efficiently, so they use ¼ inch or CNF-4 brake lines. 

#3. Are brake line metric or standard?

One end of the brake line may be metric, and the other is standard. You can generally know whether the end of the brake line is imperial or metric threaded via the vehicle’s year of origin. 

About 99% of European vehicles follow the metric method, whereas most Asian vehicles consider standard measurement of brake line as the apt way of measurement. 

What Size Brake Line Do I Need

#4. What size brake lines do I need?

Usually, it is either 3/16 inch 4.75 mm or ¼ inch size that all vehicles need. If you have customized brakes installed, it is suggested to consult your manufacturer or an expert in the field to learn about the size brake. You can also measure the size brake with the help of the instructions mentioned in the article above. 


You might like to read: What Happens If You Overfill Brake Fluid? 12 Reasons Not To Do It


A Few Final Words

Remember that there are experts to help you measure the size of the brake line of your vehicle. So, you can either do your research, learn the measurement, find the brake line’s exact size or consult a professional in the field. 

We would suggest you rather let an expert or experienced person do it instead of taking the measurement yourself to be sure about its exact size. Thank you for reading the article, we hope you got the answer you were looking for. If not, drop us a word and we will get back to you.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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