Barrel of Oil Units
How big a barrel of oil is
When you're checking oil prices, you might wonder how much a barrel holds. The oil industry uses a standard barrel that's 42 US gallons. That works out to 158.99 litres, usually quoted as 159 litres for simplicity. You'll see barrels referenced everywhere, such as in the Brent oil price charts and trading screens. This measurement is strictly volume, not weight, so barrels help buyers and sellers talk in the same terms around the globe.
This 42-gallon size goes back to the early oil trade, where real wooden barrels were filled and shipped from wells. Over time, markets settled on that size as the deal-making standard. You could still see other units in older contracts or regional negotiations, so always check what the figure means before doing a comparison.
Converting a price per barrel to a price per litre
If you need to see what an oil price means for a single litre, just divide the per-barrel cost by 159. Say a barrel is showing at 80 units, 80 divided by 159 gives about 0.50 units for each litre. This shows only the crude cost at the start of the supply chain. There’s much more: refining charges, taxes, moving the oil, and the markup at the petrol station all get added, as the process is set out in how crude prices feed through to petrol and diesel.
And if you want to go the other way, from price per litre to price per barrel, just multiply your per-litre figure by 159. Make sure you’re using the same currency for both amounts. The figure of 80 here is just for the calculation, not a current market price.
Barrels per day and tonnes of oil
Countries and companies describe oil production and demand in barrels per day, shortened as bpd. For example, one million barrels per day works out to around 159 million litres daily. Barrels-per-day figures let experts track patterns and compare over longer time periods.
Sometimes, production is also listed in metric tonnes. One tonne of crude comes out to about 7.3 barrels, but that’s only approximate. The exact conversion depends on the crude oil's density, which varies with the mix. If you’re working with specific products like heating oil or jet fuel, check for their own conversion factors.
Frequently asked questions
How many litres are in a US barrel of oil?
A US barrel of oil holds 42 US gallons, or about 158.99 litres. This is the industry’s usual standard when quoting oil prices. If you need a quick estimate from a per-barrel price, divide by 159 to get the approximate price per litre.
Is a barrel of oil the same as a barrel of petrol?
No, they’re not the same thing. The barrel just measures volume. Crude oil is processed at refineries and turned into petrol, diesel, jet fuel and other products. Each barrel of crude never maps directly to a barrel of one specific fuel. Additional costs for refining and distribution show up between the crude price and the final price for petrol or diesel.