Gallons to Pounds Calculator — Convert US Gallons to Weight
Convert US gallons to pounds by selecting the liquid or entering a custom density. Water weighs about 8.33 lb/gal; gasoline is lighter at 6.15 lb/gal; honey is much heavier at 11.85 lb/gal.
US gallons
Liquid
Pounds at the selected liquid density
- 1
Density
8.328Pounds per US gallon at approximately 68 °F (20 °C). - 2
Weight in pounds
1 × 8.328 lb/gal = 8.328
How does this calculator work?
Multiply US gallons by the liquid's density in lb/gal: water ≈ 8.33, gasoline ≈ 6.15, diesel ≈ 7.09, milk ≈ 8.60, honey ≈ 11.85. Weight (lb) = gallons × lb/gal. 1 US gallon = 3.785 litres. Densities are at room temperature (~68 °F) and vary slightly with temperature.
Formula
How this is calculated
Volume and weight cannot be exchanged without knowing the density of the liquid. This calculator stores room-temperature densities (~68 °F / 20 °C) for common substances and converts them to lb per US gallon using the exact factor 1 US gal = 3.785 411 784 L and 1 kg = 2.204 623 lb. The stored substances span a wide range: water (8.33 lb/gal) through honey (11.85 lb/gal) to mercury (112.95 lb/gal). For any liquid not listed, select "Custom density" and enter the value in lb/gal (or convert from kg/L by multiplying by 8.345).
The formula is straightforward multiplication: pounds = gallons × density. The result is also shown in ounces (× 16) and kilograms (÷ 2.205), and the volume is converted to litres using the same exact definition.
Note that density changes with temperature: hot water is less dense than cold, and petroleum products show ±2–3% variation across their typical storage range. The built-in values are approximate averages at room temperature. For custody-transfer or regulatory measurements, use the actual measured density for your specific batch at its operating temperature.
Frequently asked questions
One US gallon of water weighs approximately 8.33 pounds (3.78 kg) at 68 °F (20 °C). At 39 °F (4 °C), where water reaches its maximum density of 1.000 kg/L, it weighs about 8.34 lb/gal. The value of 8.34 lb/gal is the commonly cited standard at 62 °F.
Yes. Gasoline (petrol) has a density of roughly 0.737 kg/L, so one US gallon weighs about 6.15 pounds — about 74% of the weight of the same volume of water. This is why gasoline floats on water.
This calculator uses US gallons (1 US gal = 3.785 L). A UK (Imperial) gallon is about 20% larger: 1 UK gal = 4.546 L. To convert the result to UK gallons, multiply the displayed value by 1.201 (since 4.546 / 3.785 ≈ 1.201).
Also known as
TG we-Calculate Editorial Team. (2026). Gallons to Pounds Calculator — Convert US Gallons to Weight [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/gallons-to-pounds-calculator
TG we-Calculate Editorial Team. "Gallons to Pounds Calculator — Convert US Gallons to Weight." TG we-Calculate. 2026. https://we-calculate.com/calculator/gallons-to-pounds-calculator.
TG we-Calculate Editorial Team, "Gallons to Pounds Calculator — Convert US Gallons to Weight," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/gallons-to-pounds-calculator
@misc{wecalculate_gallons_to_pounds_calculator, title = {Gallons to Pounds Calculator — Convert US Gallons to Weight}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/gallons-to-pounds-calculator}}, year = {2026}, note = {TG we-Calculate} }
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