Gallons to Kilograms Calculator — gal to kg
Convert US or imperial gallons to kilograms and pounds for common liquids — water, gasoline, diesel, milk, ethanol, vegetable oil and honey. Weight depends on the liquid density you select.
gallons
Gallon type
Liquid
Mass of the liquid at the selected density
- 1
Volume in litres
1 × 3.785412 = 3.7851 US gallon = 3.785411784 L (exact legal definition). - 2
Weight in kilograms
3.785 × 1 = 3.785Density of the selected liquid at ~20 °C: 1 kg/L.
How does this calculator work?
Multiply gallons by the litres-per-gallon factor (3.7854 for US, 4.5461 for imperial), then by the liquid density (kg/L). Water weighs ~3.79 kg/US gal; gasoline ~2.79 kg/US gal; milk ~3.90 kg/US gal. Weight varies by liquid — volume alone does not determine mass.
Formula
How this is calculated
Volume and mass are different physical quantities — they are linked by density (mass per unit volume). One US gallon equals exactly 3.785411784 litres; one imperial gallon equals exactly 4.54609 litres. Multiplying the volume in litres by the liquid density in kg/L gives the mass in kilograms.
For water at around 20 °C the density is very close to 1.000 kg/L, so 1 US gallon of water weighs about 3.785 kg (8.34 lb). Denser liquids such as honey (≈1.42 kg/L) weigh more per gallon, while lighter liquids such as gasoline (≈0.737 kg/L) weigh less. The densities shown are approximate values at room temperature (~20 °C); they change with temperature, which can matter in engineering or shipping calculations.
Note that "gallon" is ambiguous without a qualifier: the US gallon (used in the United States) and the imperial gallon (used in the UK and Canada for some purposes) differ by about 20 %. Always confirm which gallon a source means. This calculator supports both; densities are the same regardless of gallon type — only the volume-to-litre conversion changes.
Frequently asked questions
A US gallon of water weighs approximately 3.785 kg (8.34 lb) at 20 °C. An imperial gallon weighs approximately 4.546 kg (10.02 lb). Water density of ~1.000 kg/L makes the calculation simply gallons × litres-per-gallon.
1 US gallon of gasoline weighs approximately 2.79 kg (6.15 lb), using a typical density of 0.737 kg/L. Gasoline density varies between grades and with temperature (commonly 0.720–0.760 kg/L), so this is an approximate figure.
A US gallon equals 3.785411784 litres; an imperial gallon equals 4.54609 litres — about 20 % more. The US gallon is used in the United States for fuel, beverages, and most liquids. The imperial gallon is used in the United Kingdom for fuel pricing and some contexts in Canada.
TG we-Calculate Editorial Team. (2026). Gallons to Kilograms Calculator — gal to kg [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/gal-to-kg-calculator
TG we-Calculate Editorial Team. "Gallons to Kilograms Calculator — gal to kg." TG we-Calculate. 2026. https://we-calculate.com/calculator/gal-to-kg-calculator.
TG we-Calculate Editorial Team, "Gallons to Kilograms Calculator — gal to kg," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/gal-to-kg-calculator
@misc{wecalculate_gal_to_kg_calculator, title = {Gallons to Kilograms Calculator — gal to kg}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/gal-to-kg-calculator}}, year = {2026}, note = {TG we-Calculate} }
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