Gallons to Kilograms Calculator
Convert volume in gallons to mass in kilograms using the liquid's density.
How this gallons to kg calculator works
Gallons measure volume, while kilograms measure mass. To convert gallons to kilograms, you need one extra piece of information: density. Density tells you how heavy a liquid is per liter.
This calculator first converts gallons to liters, then multiplies by density to get kilograms. Because different liquids have different densities, 1 gallon of one liquid can weigh more or less than 1 gallon of another.
Gallons to kilograms formula
kg = gallons × liters-per-gallon × density (kg/L)
- US liquid gallon = 3.785411784 liters
- Imperial gallon = 4.54609 liters
- US dry gallon = 4.40488377086 liters
If your liquid is water (density ≈ 1.0 kg/L), the conversion is straightforward. For fuels, oils, syrups, and chemicals, always check the correct density for accurate results.
Common densities (quick reference)
| Liquid | Approx. Density (kg/L) |
|---|---|
| Water | 1.000 |
| Milk | 1.030 |
| Diesel | 0.850 |
| Gasoline | 0.740 |
| Olive Oil | 0.910 |
| Honey | 1.420 |
Worked examples
Example 1: 10 US gallons of water to kg
10 × 3.785411784 × 1.000 = 37.854 kg
Example 2: 8 imperial gallons of diesel to kg
8 × 4.54609 × 0.850 = 30.913 kg (approx.)
Why your result may vary
- Temperature: Density changes with temperature.
- Product blend: Fuel grades and mixtures vary slightly by composition.
- Gallon standard: US and Imperial gallons are not the same size.
- Rounding: Small rounding differences are normal in practical calculations.
Frequently asked questions
Can I convert gallons to kg without density?
Not accurately. You can only do an exact conversion when density is known. If you assume water, you can use 1.0 kg/L.
Is this calculator for liquids only?
It is most useful for liquids. For solids or powders, use the material's bulk density and make sure your volume unit is appropriate.
What if I only know pounds per gallon?
Convert first: 1 lb/US gal ≈ 0.119826 kg/L. Then use that density in the custom field.
Final tip
For engineering, shipping, or lab work, always use a reliable density value from a product datasheet and the correct gallon type. That one detail makes the difference between a rough estimate and a trustworthy conversion.