The average density of brake fluids is about 0.95-1.1 g/ml, which translates to 7.9-9 pounds per gallon. Silicone-based DOT 5 fluids are slightly lighter with a density of 0.95-0.98 g/ml. In contrast, the density of the glycol ether-based DOT 3, DOT 4, and DOT 5.1 fluids ranges from about 1.02-1.08 g/ml.
If you want to drill into the topic, keep reading. We at PowerSportsGuide have compiled all you need to know under one roof!
What is Brake Fluid?
Brake fluid is a type of hydraulic fluid designed to transfer the force applied to the brake pedal to the brake calipers.
Depressing the brake pedal activates the “master” brake cylinder, which is connected to the brake hose filled with brake fluid.
The other end of this hose is attached to the vehicle’s brake calipers.
When you depress the brake pedal, the piston in the master cylinder generates pressure on the brake fluid. Since this fluid is incompressible, it effectively transfers the force to the brake pads, which are pressed against the brake disk.
Eventually, the friction caused by the brake pads pressing against the brake discs will slow the vehicle down.
Automotive brake fluids are used in the brake systems of cars, motorcycles, trucks, and other vehicles.
What is the Density of Brake Fluid?
It’s safe to say that there are two major types of automotive brake fluids today. The most common brake fluids are composed of Glycol Ethers, while others contain Silicium-based Polymer or Silicone.
In the United States, brake fluids are classified by the Department of Transportation (DOT) into four major categories, which are as follows:
- DOT 3 – Density at 68°F: ~ 1.02-1.04 g/ml
- DOT 4 – Density at 68°F: ~ 1.04-1.08 g/ml
- DOT 5 – Density at 68°F: ~ 0.95-0.98 g/ml
- DOT 5.1 – Density at 68°F: ~ 1.05-1.08 g/ml
Therefore, it’s safe to say that the density of most brake fluids falls into the range of 0.95-1.1 g/ml, which translates to 950-1,100 kg/m3.
Most commercially-available brake fluids fall into the DOT 3, DOT 4, and DOT 5.1 categories. They are all hygroscopic fluids, meaning that they are prone to absorbing moisture over time from the external air.
DOT 3 is the most basic fluid in this breed since it only meets the minimum specifications. These fluids are typically glycol ether-based, and their density ranges from 1.02-1.04 g/ml.
Although DOT 4 brake fluids are also glycol ether-based, they contain some borate esters for better performance. The density of DOT 4 brake fluids typically falls into the ballpark of 1.04-1.08 g/ml.
DOT 5.1 fluids are considered more advanced configurations of DOT 4 fluids, representing higher quality. They are also a mixture of glycol ether and borate ester but meet more stringent requirements. You can expect the density of a 5.1 DOT brake fluid to be in the ballpark of 1.05-1.08 g/ml.
In contrast, DOT 5 fluids are silicone-based, meaning they are not hygroscopic. Thanks to this feature, this type of brake fluid can be used in vehicles that are rarely driven, such as collector vehicles.
DOT 5 brake fluids are less dense than their glycol ether-based counterparts; their density stays below 1 g/ml (typically 0.95-0.98 g/ml).
How Much Does a Gallon of brake Fluid Weigh?
As a rule of thumb, one gallon of brake fluid weighs about 7.9-9 pounds, which is equivalent to 0.95-1.08 kilogram per liter. The weight of different types of brake fluids are as follows:
- DOT 3 weight per gallon: ~ 8.5-8.7 lbs/gal
- DOT 4 weight per gallon: ~ 8.5-9 lbs/gal
- DOT 5 weight per gallon: ~ 7.9-8.2 lbs/gal
- DOT 5.1 weight per gallon: ~ 7.8-9 lbs/gal
You can consider these figures to be hard numbers that can apply to most commercially-available brake fluids.
Brake Fluid Weight Charts
Brake Fluid Weight Comparison Chart
As a reference, we’ve compiled the specs of some popular products into this brake fluid comparison chart:
| Product | DOT | Density (g/ml) | Density (lbs/gal) |
| Eurol Brake Fluid DOT 5 Silicone | 5 | 0.95 | 7.93 |
| Kleen-Flo Silicone Brake Fluid | 5 | 0.95 | 7.93 |
| Penrite SILICONE BRAKE FLUID | 5 | 0.955 | 7.97 |
| Bel-Ray Silicone DOT 5 Brake Fluid | 5 | 0.958 | 7.99 |
| PUTOLINE DOT 5 SILICONE BRAKE FLUID | 5 | 0.967 | 8.07 |
| LUBEX BRAKE FLUID | 3 | 1.02 | 8.51 |
| MAK BRAKE FLUID SUPER | 3 | 1.023 | 8.54 |
| VURTH BRAKE FLUID | 3 | 1.031 | 8.60 |
| ATLANTIC FRENO Brake Fluid | 3 | 1.031 | 8.60 |
| Wolf Brake Fluid | 3 | 1.04 | 8.68 |
| ATLANTIC FRENO Brake Fluid | 4 | 1.04 | 8.68 |
| Mobil Brake Fluid | 4 | 1.048 | 8.75 |
| Castrol Brake Fluid | 3 | 1.05 | 8.76 |
| Repsol Brake Fluid | 5.1 | 1.05 | 8.76 |
| VURTH BRAKE FLUID | 4 | 1.052 | 8.78 |
| Finol BRAKE FLUID ESP | 4 | 1.052 | 8.78 |
| Ardina Brake Fluid | 4 | 1.06 | 8.85 |
| FOSSER Brake Fluid | 4 | 1.06 | 8.85 |
| Lubex brake fluid | 5.1 | 1.061 | 8.85 |
| PEAK Oil BRAKE FLUID | 5.1 | 1.062 | 8.86 |
| HIGHTEC BRAKE FLUID SUPER DOT 5.1 | 5.1 | 1.065 | 8.89 |
| KLONDIKE UNIVERSAL SYNTHETIC BRAKE FLUID | 5.1 | 1.067 | 8.90 |
| VURTH BRAKE FLUID SUPER | 4 | 1.069 | 8.92 |
| VURTH BRAKE FLUID | 5.1 | 1.069 | 8.92 |
| ATLANTIC FRENO Brake Fluid | 5.1 | 1.069 | 8.92 |
| Champion BRAKE FLUID | 5.1 | 1.069 | 8.92 |
| TriTech Brake Fluid | 5.1 | 1.069 | 8.92 |
| Black Bulls Brake Fluid | 4 | 1.07 | 8.93 |
| Lubrico Dot 4 brake fluid | 4 | 1.07 | 8.93 |
| Finish Line Brake Fluid | 5.1 | 1.07 | 8.93 |
| EVOLITY FTC4 Brake Fluid | 4 | 1.078 | 9.00 |
This chart is just for informational purposes only.
Brake Fluid Weight-Per-Gallon Chart
You can also see the weight per gallon figures of average brake fluids in this chart:
| Gallons | Weight (pounds) |
| 0.25 | 2-2.3 |
| 0.5 | 4-4.5 |
| 0.75 | 6-6.8 |
| 1 | 8-9 |
| 2 | 16-18 |
| 3 | 24-27 |
| 4 | 32-36 |
| 5 | 40-45 |
| 6 | 48-54 |
| 7 | 56-63 |
| 8 | 64-72 |
| 9 | 72-81 |
| 10 | 80-90 |
| 20 | 160-180 |
| 30 | 240-270 |
| 40 | 320-360 |
| 42 | 336-378 |
| 50 | 400-450 |
| 55 | 440-495 |
| 60 | 480-540 |
| 70 | 560-630 |
| 80 | 640-720 |
| 90 | 720-810 |
| 100 | 800-900 |
| 120 | 960-1080 |
| 150 | 1200-1350 |
| 200 | 1600-1800 |
| 250 | 2000-2250 |
| 300 | 2400-2700 |
| 330 | 2640-2970 |
| 350 | 2800-3150 |
| 400 | 3200-3600 |
| 500 | 4000-4500 |
This chart is just for informational purposes only. Density may vary depending on the type and the temperature.
Takeaways – FAQs About Brake Fluids
What is the density of brake fluid?
The density of brake fluids ranges from 0.95-1.1 g/ml, equal to 950-1,100 kg/m3.
What is the density of DOT 3 brake fluid?
The density of DOT 3 brake fluids typically falls into the range of 1.02-1.04 g/ml.
What is the density of DOT 4 brake fluid?
The density of DOT 3 brake fluids typically falls into the range of 1.04-1.08 g/ml.
What is the density of DOT 5 brake fluid?
The density of DOT 3 brake fluids typically falls into the range of 0.95-0.98 g/ml.
What is the density of DOT 5.1 brake fluid?
The density of DOT 3 brake fluids typically falls into the range of 1.05-1.08 g/ml.
Which is heavier water or brake fluid?
While the glycol ether-based (DOT 3, DOT 4, DOT 5.1) brake fluids are heavier than water, their silicone-based (DOT 5) counterpart is slightly lighter than water.
How much does a quart of brake fluid weigh?
One quart of brake fluid weighs about 2-2.25 pounds.
How much does a gallon of brake fluid weigh?
One gallon of brake fluid weighs about 7.9-9 pounds.
How much do 2 gallons of brake fluid weigh?
Two gallons of brake fluid weigh about 15.8-18 pounds.
How much do 3 gallons of brake fluid weigh?
Three gallons of brake fluid weigh about 24-27 pounds.
How much do 4 gallons of brake fluid weigh?
Four gallons of brake fluid weigh about 32-36 pounds.
How much do 5 gallons of brake fluid weigh?
Five gallons of brake fluid weigh about 40-45 pounds.
How much do 6 gallons of brake fluid weigh?
Six gallons of brake fluid weigh about 48-54 pounds.
How much do 7 gallons of brake fluid weigh?
Seven gallons of brake fluid weigh about 56-63 pounds.
How much do 8 gallons of brake fluid weigh?
Eight gallons of brake fluid weigh about 64-72 pounds.
How much do 9 gallons of brake fluid weigh?
Nine gallons of brake fluid weigh about 72-81 pounds.
How much do 10 gallons of brake fluid weigh?
Ten gallons of brake fluid weigh about 80-90 pounds.
How much do 20 gallons of brake fluid weigh?
Twenty gallons of brake fluid weigh about 160-180 pounds.
How much do 30 gallons of brake fluid weigh?
Thirty gallons of brake fluid weigh about 240-270 pounds.
How much do 40 gallons of brake fluid weigh?
Forty gallons of brake fluid weigh about 320-360 pounds.
How much do 42 gallons of brake fluid weigh?
Forty two gallons of brake fluid weigh about 336-378 pounds.
How much do 50 gallons of brake fluid weigh?
Fifty gallons of brake fluid weigh about 400-450 pounds.
How much do 55 gallons of brake fluid weigh?
Fifty five gallons of brake fluid weigh about 440-495 pounds.
How much do 60 gallons of brake fluid weigh?
Sixty gallons of brake fluid weigh about 480-540 pounds.
How much do 70 gallons of brake fluid weigh?
Seventy gallons of brake fluid weigh about 560-630 pounds.
How much do 80 gallons of brake fluid weigh?
Eighty gallons of brake fluid weigh about 640-720 pounds.
How much do 90 gallons of brake fluid weigh?
Ninety gallons of brake fluid weigh about 720-810 pounds.
How much do 100 gallons of brake fluid weigh?
One hundred gallons of brake fluid weigh about 800-900 pounds.
How much do 120 gallons of brake fluid weigh?
One hundred and twenty gallons of brake fluid weigh about 960-1080 pounds.
How much do 150 gallons of brake fluid weigh?
One hundred and fifty gallons of brake fluid weigh about 1200-1350 pounds.
How much do 200 gallons of brake fluid weigh?
Two hundred gallons of brake fluid weigh about 1600-1800 pounds.
How much do 250 gallons of brake fluid weigh?
Two hundred and fifty gallons of brake fluid weigh about 2000-2250 pounds.
How much do 300 gallons of brake fluid weigh?
Three hundred gallons of brake fluid weigh about 2400-2700 pounds.
How much do 330 gallons of brake fluid weigh?
Three hundred and thirty gallons of brake fluid weigh about 2640-2970 pounds.
How much do 400 gallons of brake fluid weigh?
Four hundred gallons of brake fluid weigh about 3200-3600 pounds.
How much do 500 gallons of brake fluid weigh?
Five hundred gallons of brake fluid weigh about 4000-4500 pounds.
References:
https://www.autoserviceworld.com/carsmagazine/brake-fluids/
https://www.rymax-lubricants.com/updates/what-is-brake-fluid/
https://www.machinerylubrication.com/Read/30614/know-brake-fluids
