A gallon of water weighs approximately 8.34 pounds (about 3.78 kilograms) at room temperature (around 68–70°F or 20–21°C)
. This weight corresponds to a US gallon, which is defined as 128 fluid ounces or 3.785 liters
. The exact weight can vary slightly depending on temperature, as water is densest at about 39.2°F (4°C), where a gallon weighs about 8.345 pounds. Warmer water weighs a bit less due to expansion and lower density, while colder water weighs slightly more because it is denser
. In summary:
- US gallon of water ≈ 8.34 pounds (3.78 kg) at room temperature
- Weight varies slightly with temperature, pressure, and gravity but generally close to 8.34 pounds per gallon
This is the standard reference value used for most practical purposes.
