A barrel of crude oil is 42 US gallons (159 liters, 35 imperial gallons) and weighs about 300 pounds for light crude. Refined, it yields roughly 45 gallons of products — mostly gasoline and diesel — thanks to processing gain. Here's what's inside, and why the unit is 42 gallons in the first place.
| Product | Gallons | Share | Yield |
|---|---|---|---|
| Gasoline | 19.4 | 43% | |
| Diesel & heating oil | 12.5 | 28% | |
| Jet fuel / kerosene | 4.1 | 9% | |
| Heavy fuel oil & asphalt | 2.3 | 5% | |
| LPG (propane, butane) | 1.9 | 4% | |
| Petrochemical feedstock, lubricants & other | 4.8 | 11% |
Typical US refinery yield per 42-gallon barrel (EIA averages, rounded). Output exceeds 42 gallons because refined products are less dense than crude — the industry calls this processing gain. Actual yields vary with crude grade and refinery configuration; see the glossary for light/heavy and sweet/sour distinctions.
One barrel of crude oil is exactly 42 US gallons, equal to about 159 liters or 35 imperial gallons. Oil prices quoted per barrel (like WTI and Brent) always refer to this 42-gallon unit.
A typical US refinery turns one 42-gallon barrel of crude into roughly 19–20 gallons of gasoline and 11–13 gallons of diesel and other distillates, plus about 4 gallons of jet fuel and a mix of heavier products (asphalt, lubricants, petrochemical feedstock, LPG). Total output is about 45 gallons — more than went in — because refined products are less dense than crude ("processing gain").
It depends on density. Light crude like WTI (~40° API) weighs roughly 300 pounds (135 kg) per barrel; heavy crudes can exceed 320 pounds. As a rule of thumb, about 7.3 barrels of light crude weigh one metric tonne.
The standard dates to 1860s Pennsylvania, where early producers shipped oil in used 42-gallon wooden tierces — a common cooperage size sturdy enough to haul by wagon. The Petroleum Producers Association adopted 42 gallons as the standard in 1872, and it stuck even though oil hasn't moved in actual barrels for a century.
About 5.8 million British thermal units (MMBtu), or roughly 1,700 kWh of thermal energy — the basis for "barrel of oil equivalent" (BOE) comparisons across fuels. One barrel holds about the same energy as 5.6 Mcf of natural gas.