Weight depends on the liquid, not just the gallons
There is no single gallons-to-pounds number. A gallon is a volume, and how much it weighs depends on what fills it. Water is 8.34 lb per US gallon; honey is nearly 12. Pick the liquid, then multiply.
Weight per gallon, by liquid
| Liquid | 1 US gal | 5 US gal | 10 US gal |
|---|---|---|---|
| Water | 8.34 lb | 41.7 lb | 83.4 lb |
| Whole milk | 8.64 lb | 43.2 lb | 86.4 lb |
| Gasoline | 6.20 lb | 31.0 lb | 62.0 lb |
| Diesel | 7.10 lb | 35.5 lb | 71.0 lb |
| Honey | 11.85 lb | 59.3 lb | 118.5 lb |
These are at about 68°F. Density shifts a little with temperature — roughly 0.4% for water across its liquid range, but enough to matter commercially for fuels.
A US gallon and a UK gallon are not the same size
The imperial (UK) gallon is 20% larger than the US gallon, so it weighs 20% more for the same liquid. Confusing the two is the most common mistake here.
A gallon of water weighs 10.02 lb in the UK but 8.34 lb in the US — a 1.68 lb gap that comes entirely from the two gallons being different volumes.
Common questions
How much does a gallon of water weigh?
A US gallon of water weighs about 8.34 pounds at room temperature. An imperial (UK) gallon of water weighs about 10.02 pounds, because it holds 20% more.
Why does a gallon of honey weigh more than a gallon of gasoline?
Because they have different densities. A gallon is a fixed volume, but honey packs about 11.85 pounds into it while gasoline is only 6.2 pounds. The liquid matters as much as the gallon count.
How much does a gallon of milk weigh?
A US gallon of whole milk weighs about 8.64 pounds. Milk is slightly denser than water because of its protein, lactose and mineral content.
