Enter US gallons and choose a liquid to see how much it weighs in pounds and kilograms, or switch direction to turn pounds into gallons. Pick from common liquids or type your own specific gravity.
Last updated:
Direction
US gal
lb
Density relative to water (water = 1). Found on safety data sheets.
Enter your values to see the result.
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How to use the Gallons to Pounds Converter
Choose the direction: gallons to pounds or pounds to gallons.
Enter the amount in US gallons or pounds.
Pick the liquid, or choose Custom and type its specific gravity.
Read the result in pounds (or gallons), plus kilograms, liters and the reverse factor.
Compare liquids in the table and copy or download the results.
Gallons to pounds formula
A gallon is a volume and a pound is a weight, so you need the liquid's density. With specific gravity (SG, the density relative to water):
pounds = US gallons × 8.3372 × SG
8.3372 lb is the weight of one US gallon (3.785 L) of pure water at 60 °F (15.6 °C). Example: 15 gallons of gasoline (SG 0.74) weigh 15 × 8.3372 × 0.74 = 92.5 lb. To go the other way divide: gallons = pounds ÷ (8.3372 × SG), so 20 lb of propane is 20 ÷ 4.227 = 4.73 gallons.
Weight of one gallon of common liquids
Liquid
Specific gravity
lb per US gallon
kg per US gallon
lb per UK gallon
Water
1
8.34
3.78
10.01
Seawater
1.025
8.55
3.88
10.26
Milk (whole)
1.033
8.61
3.91
10.34
Gasoline
0.74
6.17
2.80
7.41
Diesel fuel
0.85
7.09
3.21
8.51
Kerosene / jet fuel
0.8
6.67
3.03
8.01
Ethanol
0.789
6.58
2.98
7.90
Propane (liquid)
0.507
4.23
1.92
5.08
Vegetable oil
0.92
7.67
3.48
9.21
Olive oil
0.915
7.63
3.46
9.16
Motor oil
0.88
7.34
3.33
8.81
Antifreeze (ethylene glycol)
1.113
9.28
4.21
11.14
Honey
1.42
11.84
5.37
14.22
Maple syrup
1.33
11.09
5.03
13.32
Typical values near 60 °F. Gasoline (about 0.71–0.77), diesel and oils vary by blend and season; honey varies with moisture content. A UK (imperial) gallon is 1.201 US gallons, so it weighs 20% more.
Good to know
Temperature matters. Liquids expand when warm, so a gallon weighs slightly less. Water is 8.34 lb/gal at room temperature but about 8.0 lb/gal near boiling.
Propane tanks are filled by weight. A standard "20 lb" grill cylinder holds about 4.7 gallons of liquid propane.
Shipping and towing: use the pounds result to check payload, trailer or shelf limits; a 55-gallon drum of water weighs about 459 lb before the drum itself.
Fluid ounces vs ounces: 128 fl oz make a gallon, but a gallon of water weighs about 133 oz. The weight-in-ounces result above is avoirdupois ounces.
Frequently asked questions
How much does a gallon of water weigh?
A US gallon of water weighs about 8.34 pounds (3.78 kg) at room temperature. At 60 °F the exact figure is about 8.337 lb.
How do I convert gallons to pounds?
Multiply the gallons by the liquid's weight per gallon. For any liquid, pounds = gallons × 8.3372 × specific gravity. For example, 10 gallons of diesel (SG 0.85) weigh about 70.9 lb.
How much does a gallon of milk weigh?
A gallon of whole milk weighs about 8.6 pounds, slightly more than water because milk has a specific gravity of about 1.03.
How much does a gallon of gasoline weigh?
Roughly 6 to 6.3 pounds, depending on the blend and temperature. This tool uses a typical specific gravity of 0.74, about 6.17 lb per gallon.
How many gallons are in a 20 lb propane tank?
Liquid propane weighs about 4.23 lb per gallon, so 20 lb is about 4.7 gallons.
What is specific gravity?
Specific gravity is the density of a liquid divided by the density of water. Water is 1.0; anything lighter, like oil or gasoline, is below 1 and floats on water, and anything heavier, like honey, is above 1.
Is a UK gallon heavier than a US gallon?
Yes. An imperial gallon is 4.546 L versus 3.785 L for a US gallon, so a UK gallon of water weighs about 10.02 lb compared with 8.34 lb.
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