Oil Barrel Converter (bbl to liters & m³)

Understanding the oil barrel converter — concept and principle

Crude oil prices, production figures and refinery capacities are quoted in barrels (bbl) and barrels per day, while many countries buy, store and tax fuel in litres, kilolitres or cubic metres. This converter moves a volume between petroleum barrels, litres, cubic metres, kilolitres and US gallons, so you can read an oil-market headline in units you can picture.

How it is calculated

The value is converted to litres, then divided by the size of the target unit. The definitions are exact:

• 1 petroleum barrel = 42 US gallons
• 1 US gallon = 231 cubic inches = 3.785411784 L
• 1 barrel = 42 × 3.785411784 = 158.987294928 L ≈ 0.158987 m³
• 1 m³ = 1 kL = 1,000 L ≈ 6.28981 barrels

The principle

The barrel is a customary unit that the early US oil industry settled on, and it was later tied to the US gallon so that it has an exact metric value. Because the US gallon is defined as exactly 231 in³ and the inch as exactly 2.54 cm, every step of the chain is exact: 231 × 2.54³ cm³ = 3,785.411784 cm³, and 42 of those make 158,987.294928 cm³. No physical property of the oil enters the calculation; it is purely a volume conversion.

Worked example

Default input: 1 barrel of oil to litres.

1. 1 bbl = 42 US gal.
2. 42 × 3.785411784 L = 158.9872949 L.
3. In cubic metres or kilolitres: 158.987 ÷ 1,000 = 0.1589872949.
4. Back in US gallons: 42.

How to read the result

About 159 litres is roughly the fuel in three to four mid-size car tanks. A cubic metre (1 kL) is a little under 6.3 barrels. Oil prices are quoted per barrel, so dividing a price per barrel by 158.987 gives a price per litre of crude, before refining, transport and taxes. At $80 per barrel that is about $0.50 per litre; the same division works in any currency. If you need mass rather than volume, multiply litres by the oil's density: at 0.85 kg/L, one barrel weighs about 135 kg, but crudes range from light to heavy, so barrels per tonne vary.

Common mistakes

• Using a 55-gallon steel drum as if it were a barrel of oil; drums are a different size.
• Confusing petroleum barrels with US beer barrels (31 US gal) or other customary barrels.
• Using UK (imperial) gallons, which are larger: 1 imp gal = 4.54609 L.
• Converting barrels to tonnes with one fixed factor without checking the oil's density.

Frequently asked questions

How many litres are in a barrel of oil?

Exactly 158.987294928 L, usually rounded to 159 L.

How many barrels are in a cubic metre?

About 6.2898 barrels.

How many gallons in a barrel?

42 US gallons, or about 34.97 imperial gallons.

What does "barrels per day" mean in litres?

Multiply by 158.987. For example, 100,000 bbl/d is about 15.9 million litres per day.

Sources: NIST Special Publication 811 (2008), Appendix B (barrel for petroleum, 42 US gallons) · NIST Handbook 44, Appendix C, General Tables of Units of Measurement