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How Much Does a Gallon of Gas Weigh?
Updated Measurements & Conversions
Why gas is lighter than water: weight comes down to density, and gasoline is a mix of hydrocarbons that's significantly less dense than water — roughly 74–76% as dense, which is why gasoline floats on water rather than mixing with it.
Weight by fuel type (approximate, per US gallon)
| Fuel | Weight |
|---|---|
| Regular gasoline | ≈ 6.3 lb (2.8 kg) |
| Premium gasoline | ≈ 6.1–6.3 lb (varies slightly by formulation) |
| Diesel | ≈ 7.1 lb (3.2 kg) — diesel is denser than gasoline |
| Water (for comparison) | ≈ 8.3 lb (3.8 kg) |
Why the exact figure isn't perfectly fixed: gasoline's exact density varies slightly by season, region, and additive blend (e.g., ethanol content), and temperature affects it too — gasoline expands slightly and gets marginally lighter per gallon as it warms, and contracts slightly when cold.
Why this comes up practically: a full 15-gallon tank of gasoline weighs roughly 94–95 pounds, which matters for things like calculating a vehicle's loaded weight, understanding fuel weight in aviation or boating (where weight and balance genuinely affects performance), or basic curiosity about a substance most people handle constantly without thinking about its weight.
Two similar answers: How Much Does a Gallon of Water Weigh? and How Much Is 8 oz in Cups?.
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