The weight of a gallon of water depends on the temperature, as water density changes slightly with temperature. However, the standard weight of a gallon of water at its maximum density (approximately 4°C or 39°F) is:
U.S. Gallon
- 1 U.S. gallon of water (128 fluid ounces) weighs approximately 8.34 pounds (3.785 kilograms).
Imperial Gallon
- 1 Imperial gallon of water (160 fluid ounces, used in the UK) weighs approximately 10.02 pounds (4.546 kilograms).
Factors That Affect Weight
- Temperature:
- Water is most dense at 4°C (39°F). As the temperature increases or decreases, water expands slightly, reducing its density and therefore its weight.
- Salinity:
- Saltwater is denser than freshwater, so a gallon of saltwater weighs more.
Quick Reference Table
| Type of Gallon | Weight |
|---|---|
| U.S. Gallon | 8.34 pounds (3.785 kg) |
| Imperial Gallon | 10.02 pounds (4.546 kg) |