An oil barrel is 42 US gallons.
Oil barrels to Gallons Converter — bbl to gal
Convert Oil barrel (bbl) to Gallon (gal) using the exact conversion factor (1 oil barrel = 42 gallon). See the formula, worked examples, conversion table, history, and common uses.
Oil barrels to Gallons converter
Converter
Volume Converter
Convert metric, US customary, imperial, cooking, dry, and industrial volume units.
Context values
Some unit families need one extra value for a physically accurate result.
A US liquid gallon is exactly 3.785411784 liters.
Result = input x 0.1589872949 / 0.003785411784.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Oil barrels to Gallons
Oil barrel and Gallon appear side by side at fuel pumps and on beverage labels, since the US measures liquids in gallons while most of the world uses liters. Specifically: An oil barrel is 42 US gallons, and a US liquid gallon is exactly 3.785411784 liters.
Formula
gallons = oil barrels × 42
This factor comes from each unit's defined relationship to the category's base unit: 1 oil barrel equals 0.158987294928 base units, and 1 gallon equals 0.003785411784 base units, so dividing one by the other gives the direct oil barrel-to-gallon factor of 42.
Simple example
1 bbl × 42 = 42 gal
1 oil barrel = 42 gallons.
Real-world example
10 bbl × 42 = 420 gal
10 oil barrels = 420 gallons.
Conversion table
| Oil barrel (bbl) | Gallon (gal) |
|---|---|
| 1 bbl | 42 gal |
| 5 bbl | 210 gal |
| 10 bbl | 420 gal |
| 25 bbl | 1,050 gal |
| 50 bbl | 2,100 gal |
| 100 bbl | 4,200 gal |
Reverse conversion: Gallon to Oil barrel
42 gal × 0.02380952381 = 1 bbl
42 gallons = 1 oil barrel.
oil barrels = gallons × 0.0238095238095
For a page dedicated to this direction, see Gallon to Oil barrel.
Understanding the Oil barrel (bbl)
An oil barrel is 42 US gallons.
Understanding the Gallon
Gallon (gal) measures volume. The US liquid gallon is defined as exactly 231 cubic inches, equal to 3.785411784 liters. It is classified as a US customary unit.
Where it's used: United States (fuel, beverage, and liquid measurement)
US gallon vs. imperial gallon. The US liquid gallon (3.785411784 L) and the British imperial gallon (4.54609 L) are different units with the same name; always confirm which one a source is using.
Uses of the Gallon today
- Fuel pump and vehicle fuel-economy measurement in the US
- Beverage and liquid product packaging in the US
- Cooking and recipe measurement in US customary units
History of the Gallon
The US gallon descends from the English wine gallon of 231 cubic inches, a standard used for measuring wine in medieval and early modern England, which the American colonies inherited and retained even after England moved to a different imperial gallon in 1824.
England's 1824 Weights and Measures Act replaced the old wine gallon with a new imperial gallon (based on 10 pounds of water), but the US kept the older 231-cubic-inch definition — which is why the US gallon (3.785 L) and the imperial gallon (4.546 L) differ by about 20% today.
Historical origin. Gallon was not the invention of a single named person; it developed through the process described above.
Gallon — sources
- NIST Handbook 44, Appendix C — General tables of units of measurement, including the US gallon definition.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many gallons are in 1 oil barrel?
1 oil barrel equals 42 gallons, using the exact defined conversion factor rather than an estimate.
How do I convert oil barrel to gallon?
Multiply the oil barrel value by 42. The converter above does this instantly to whatever precision you set.
How do I convert gallon back to oil barrel?
Use the reverse factor: 1 gallon equals 0.0238095238 oil barrels. You can also use the swap control in the converter above to flip the direction instantly.
What is a oil barrel?
Oil barrel (bbl) is a unit of volume.
What is a gallon?
Gallon (gal) measures volume. The US liquid gallon is defined as exactly 231 cubic inches, equal to 3.785411784 liters. It is classified as a US customary unit.
Is the oil barrel to gallon conversion exact?
Yes. The US liquid gallon is defined as exactly 231 cubic inches, equal to 3.785411784 liters. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between us gallon vs. imperial gallon?
The US liquid gallon (3.785411784 L) and the British imperial gallon (4.54609 L) are different units with the same name; always confirm which one a source is using.