Oil barrel and volume converter
Convert crude oil between barrels, litres, US gallons, cubic metres and metric tonnes.
Quick answer: One oil barrel is 42 US gallons, or about 159 litres. Turning barrels into tonnes needs density: at 850 kg/m³, about 7.4 barrels weigh one metric tonne.
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Convert oil without mixing up volume and mass
How to use this calculator
- Choose the unit you have and the unit you need.
- Enter the amount. For barrels, litres, gallons and cubic metres, that is all you need.
- If tonnes are involved, enter the crude density in kg/m³. Heavier crude has a higher number.
Converting 1 barrel at the prefilled 850 kg/m³ gives about 158.99 litres and about 0.135 metric tonnes. Change the density to 900 kg/m³ and the tonne figure rises to about 0.143, while the litre figure stays the same.
Barrels measure space, tonnes measure weight
A barrel is a volume: exactly 42 US gallons, or about 158.987 litres. A metric tonne is a mass. You can only move between the two with a density, because a heavy crude packs more kilograms into each barrel than a light one.
Why density changes the answer
At 850 kg/m³, one barrel weighs about 135 kg, so roughly 7.4 barrels make a tonne. At 950 kg/m³, the same tonne fills only about 6.6 barrels. A small density change moves a large cargo total.
Temperature is not included
Oil expands when it warms. Traded volumes are usually corrected to a standard temperature, such as 60°F in the United States or 15°C elsewhere. This converter does not apply that correction.
Where to go next
Not sure of the density? Read the crude oil quality guide, or turn a lab reading into kg/m³ with the API gravity converter. Once you know the barrels, the crude cargo value calculator puts a price on them.
Questions about this calculation
How many litres are in a barrel of oil?
One oil barrel is exactly 42 US gallons, which is about 158.987 litres.
How many barrels are in a tonne of crude oil?
It depends on density. Published averages are around 7.3 barrels per tonne, but a light crude near 820 kg/m³ gives about 7.7 and a very heavy crude near 1,000 kg/m³ gives about 6.3. Enter your own density for a specific figure.
Is an oil barrel the same as a steel drum?
No. The 42-gallon oil barrel is a unit of measurement. Physical steel drums commonly hold 55 US gallons.
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