How many US gallons are in one barrel?

One US oil barrel equals exactly 42 US liquid gallons. This is the standard barrel size used in the petroleum industry and defined by US Customary units.

Is this the same as a beer barrel or wine barrel?

No. A US beer barrel is 31 gallons, a US wine barrel is typically 59.4 gallons, and a UK barrel is about 36 imperial gallons. This tool converts the US oil barrel (42 US gallons), which is the standard unit in petroleum trade.

How do I convert gallons back to barrels?

Click the swap button or select the "Gallons → Barrels" direction, then enter the number of gallons. The converter divides by 42 to give you the barrel count.

Why is the oil barrel 42 gallons?

The 42-gallon barrel was standardized in the mid-1800s by Pennsylvania oil producers. They chose 42 gallons (from the old English "tierce" wine cask) to allow for spillage and evaporation losses during transport, and the convention stuck industry-wide.

Does this converter work for imperial gallons?

No, this tool uses US liquid gallons only (1 US gallon ≈ 3.785 liters). For imperial gallons (1 imp. gal ≈ 4.546 liters), use a dedicated imperial converter.

Barrels to US Gallons Converter

Convert US oil barrels (bbl) to US liquid gallons instantly, or reverse from gallons back to barrels.

Volume Converter

Barrels (bbl)

US Gallons (gal)

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1 US oil barrel = 42 US liquid gallons (exact)

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Quick Reference Table

Barrels (bbl)	US Gallons (gal)

US Gallons (gal)	Barrels (bbl)

US oil barrel = 42 US liquid gallons • 1 US gallon ≈ 3.785 liters

Summary

This tool converts US oil barrels (bbl) to US liquid gallons (gal) using the exact factor of 42 gallons per barrel — the standard defined by the US Customary system and widely used in the petroleum industry. You can also reverse the conversion to find how many barrels a given number of gallons equals. The reference table covers the most common barrel quantities so you can look up results without typing a number.

How it works

Select a conversion direction: barrels to gallons or gallons to barrels.
Enter a value in the input field.
The converter instantly shows the result using the exact 42-gallon-per-barrel factor.
Use the swap button to flip the direction.
Scroll down to the reference table for common barrel-to-gallon lookups.

Use cases

Convert crude oil volumes from barrels to gallons for purchasing or logistics.
Check petroleum storage capacity when equipment is rated in gallons.
Translate production reports that mix barrel and gallon units.
Verify tank fill calculations for fuel distributors.
Convert OPEC production figures (barrels/day) to gallon equivalents.
Homework and exam problems involving US volume unit conversions.

Frequently Asked Questions

Last updated: 2026-06-14 · Reviewed by Nham Vu