Gallons measure volume and pounds measure weight — converting between them depends on the liquid’s density, not a fixed ratio.
How it works
Multiplying gallons by the exact US gallon volume (3,785.41 mL) and the liquid’s density gives grams, then dividing by 453.59237 (grams per pound) gives pounds. The default density is water’s.
What this does not include
This does not include a built-in density lookup for specific liquids — check a reliable source for the exact density of whatever liquid you’re measuring if it isn’t water.
How to use this calculator
- Enter the gallons and the liquid’s density (defaults to water).
Frequently asked questions
Why doesn’t a gallon have one fixed weight?
Because a gallon is a fixed volume, and different liquids pack different amounts of mass into that same volume.
How much does a gallon of water weigh?
About 8.345 pounds at standard conditions, the default result of this calculator.
Is gasoline heavier or lighter than water per gallon?
Lighter — gasoline is less dense than water (roughly 0.74 g/mL), so a gallon of gasoline weighs noticeably less than a gallon of water.
