How much does 55 gallons of water weigh?

"Gallons to Pounds" Calculator
How many pounds in
gal

How much does 55 gallons of water weigh?

Answer

55 US gallons of water weighs
458.1 lbs

Water is taken at 20 °C (68 °F), where its density is 0.998 kg/L, so one US gallon of it weighs 8.33 lbs. Colder water is a touch denser and weighs slightly more; warmer water slightly less.

In imperial (UK) gallons of 4.54609 L instead of 3.785411784 L, 55 UK gallons of water would weigh 550.1 lbs.

How the weight of 55 gallons of water was worked out

pounds = gallons × density (kg/L) × 3.785411784 ÷ 0.45359237

A US gallon is exactly 3.785411784 liters and a pound is exactly 0.45359237 kilograms, so the density in kilograms per liter turns into pounds per gallon by multiplying by the first and dividing by the second.

55 gal × 0.998 kg/L × 3.785411784 ÷ 0.45359237

≈

458.1 lbs

(four hundred fifty-eight point one lbs)

The density comes from FAO/INFOODS Density Database v2.0: liquid water at 20 °C; rounding to 1.00 kg/L is fine for everyday use.

Why the same gallon weighs differently

A gallon measures volume, a pound measures weight, and density is what ties them together: how many pounds one US gallon of this particular substance comes to. Water is the everyday reference at 8.33 lbs per gallon, and everything else sits above or below it.

Across this page the spread is wide: one US gallon of propane weighs 4.24 lbs, one US gallon of milk 8.6 lbs — at the very same volume.

If the substance is not known in advance, start from how many pounds 55 gallons is — the same volume across every substance at once.

The other way round: how many gallons a weight fills

This page starts from a volume and answers in pounds. The opposite question — how many gallons a given weight comes to — is what the pounds to gallons calculator is for, and in metric units the same question is kilograms to liters. All of them read one density table, so their numbers agree.

For water that means 55 gallons weighs 458.1 lbs here, and one pound of it fills 0.12 gallons there.

Related Calculations

See Also

  • Pounds to Gallons - How many gallons a pound of water, milk, oil or propane takes — by density
  • Liters to Pounds - How much a liter of water, gasoline or propane weighs in pounds — by density
  • Liters to Kilograms - How many kilograms are in a liter of water, honey, gasoline, sand and other substances — by density
  • Gallons to Liters - Convert US Gallons to Liters
  • Lbs to Kg - Convert Pounds to Kilograms

About "Gallons to Pounds" Calculator

This calculator converts US gallons to pounds through the density of the substance: weight equals volume times density. A gallon on its own has no weight — a gallon of water weighs 8.33 lbs, a gallon of gasoline 6.18 lbs and a gallon of propane only 4.24 lbs. When no substance is named, the answer is for water, and the table shows every other liquid next to it. For example, it can help you find out how much does 55 gallons of water weigh? (The answer is: 458.1). The gallon here is the US liquid gallon of 231 cubic inches; the imperial gallon used in the UK is a fifth larger, and every result page names what the same number of imperial gallons would weigh.
"Gallons to Pounds" Calculator
How many pounds in
gal

How much 55 gallons of each substance weighs

SubstanceWeight of 55 gallonsOne US gallonDensity, kg/L
Diesel382.8 lbs6.96 lbs0.834
Gasoline339.7 lbs6.18 lbs0.74
Milk472.8 lbs8.6 lbs1.03
Propane233 lbs4.24 lbs0.5076
Vegetable oil422.3 lbs7.68 lbs0.92
Water458.1 lbs8.33 lbs0.998

FAQ

How much does 55 gallons of water weigh?

55 US gallons of water weighs 458.1 lbs

How do you work out the weight of 55 gallons of water?

Weight equals volume times density. The density of water is 0.998 kg/L and a US gallon is exactly 3.785411784 liters and a pound is exactly 0.45359237 kilograms, so 55 gallons weighs 458.1 lbs — the figure is rounded, so multiplying the printed numbers can differ in the last digit.

Why do some tables say a gallon of water weighs a little more?

Because water changes density with temperature. This page takes water at 20 °C (68 °F), where its density is 0.998 kg/L and a US gallon weighs 8.33 lbs. Water is densest at 4 °C (39 °F) — one kilogram per liter — and a US gallon of it then weighs 8.35 lbs. The figure most US tables quote lies between the two: it assumes water at 60–62 °F, the reference temperature for liquids in US trade.

What does 55 UK gallons of water weigh?

55 UK gallons of water weighs 550.1 lbs against 458.1 lbs for the same number of US gallons: the imperial gallon is 4.54609 liters, the US one 3.785411784. The imperial gallon was defined in 1824 as the volume of ten pounds of water, which is why one UK gallon of water still weighs close to ten pounds.

See Also