What is a gallons to kg conversion?
A gallons to kilograms converter changes a volume in US gallons into a weight in kilograms. A gallon describes how much space a liquid takes up, while a kilogram describes its mass, so the conversion depends on the density of whatever fills the gallon. A gallon of gasoline weighs less than a gallon of water, and a gallon of honey weighs more.
Choose a product—water, milk, oil, fuel, honey and others—or supply a custom density, and the calculator applies the correct value. It also runs in reverse, letting you enter kilograms to find gallons.
How does it work?
Weight equals volume times density. The tool keeps densities in pounds per US gallon, multiplies your gallons by that density to get pounds, then converts pounds to kilograms (1 lb = 0.45359237 kg):
Water’s density of about 8.34 lb/gal works out to roughly 3.785 kg per US gallon—the same as the 3.78541 liters in a gallon, since a liter of water masses about one kilogram.
Formula
Worked examples
Example 1: One gallon of water
Example 2: Two gallons of water
Approximate conversions for water
| Volume (US gal) | Weight (kg) |
|---|---|
| 0.5 | 1.89 |
| 1 | 3.79 |
| 2 | 7.57 |
| 5 | 18.93 |
| 10 | 37.85 |
Notes
These values assume US gallons. One US gallon equals 3.78541 liters, whereas an imperial (UK) gallon is larger at 4.54609 liters, so the same number of imperial gallons weighs more. Density also drifts a little with temperature and composition, so use the figures as reliable estimates. To convert a density between unit systems, use our density unit converter.
Frequently Asked Questions
How many kilograms does a gallon of water weigh?
About 3.785 kilograms for a US gallon, matching the mass of the 3.78541 liters it contains.
Does fuel weigh the same as water?
No. Gasoline is lighter than water at roughly 6.2 lb/gal, so a gallon of gasoline weighs less than a gallon of water. Diesel is a little heavier than gasoline but still lighter than water.
Is this for US or imperial gallons?
The default is the US gallon. Switch the volume unit to gal (UK) if you are working with imperial gallons.