US Gallons to oil barrels
1 US gal = 0.0238095 bbl, derived from exact unit definitions.
| US gal | bbl |
|---|---|
| 42 US gal | 1.0000 bbl |
| 100 US gal | 2.3810 bbl |
| 275 US gal | 6.5476 bbl |
| 500 US gal | 11.9048 bbl |
| 1,000 US gal | 23.8095 bbl |
| 5,000 US gal | 119.0476 bbl |
oil barrels = US gallons ÷ 42
= US gallons × 0.0238095238095… (repeating)Divide by 42. The reciprocal 1/42 repeats the block 238095 forever, so any multiplier you write down is rounded.How to convert US gallons to oil barrels
Divide by 42. You need this whenever a volume measured or delivered in gallons has to be reported in the unit the petroleum industry keeps its books in.
- Confirm the target is the petroleum barrel of 42 US gallons, not a beer barrel (31 gal) or a drum (55 gal).
- Divide the gallon figure by 42.
- Check the magnitude: barrels should be a little over 2 % of the gallon figure.
A tanker load
- Delivered: 8,400 US gal
- 8400 ÷ 42 = 200.0 bbl
8,400 US gal = 200 bbl exactly
Tank truck compartments are often sized to whole barrel counts for exactly this reason — it keeps the paperwork clean at both ends.
A 12,000-gallon delivery
- 12000 ÷ 42 = 285.714285…
- Report as 285.71 bbl
12,000 US gal = 285.71 bbl
A single 55-gallon drum
- 55 ÷ 42 = 1.3095 bbl
- A pallet of four drums = 220 gal = 5.238 bbl
55 US gal = 1.31 bbl
Worth stating explicitly on any document where drums and barrels both appear. The two words are used interchangeably in speech and never mean the same thing on paper.
Where the factor comes from
1 bbl ≡ 42 US gal (43 CFR § 3174.2)
1 gal = 1/42 bbl
= 0.023809523809523… repeating, period 6
1 gal = 3.785411784 L
1 bbl = 158.987294928 L exactly42 = 2 × 3 × 7. The factors of 3 and 7 are why the decimal never terminates.Rounding
0.0238095 is accurate to 0.0001 %. 0.0238 is 0.04 % low. 0.024 is 0.8 % high — on a 100,000-gallon movement that is 19 barrels of phantom volume, which is not a rounding anyone wants to explain. Divide by 42.
FAQ
How many barrels is 1,000 gallons?
23.81 barrels — 1,000 ÷ 42 = 23.809523… For any figure, dividing by 42 is exact while multiplying by a rounded 0.0238 is not.
Is a drum a barrel?
No. A standard steel drum holds 55 US gallons, or 1.31 petroleum barrels. Barrels are a unit of account in the oil industry; drums are physical containers.
What about a beer barrel?
A US beer barrel is 31 US gallons — a different unit entirely, used in brewing and in federal alcohol excise reporting.
Why does my barrel figure not match the invoice?
Usually a temperature basis mismatch rather than an arithmetic error. Oil is traded as standard volume at 60 °F, so an observed gallon reading taken warm converts to more barrels than the corrected figure the invoice is built on.
Sources and standards
Every factor on this page is traced to the document that defines it. Where a value is exact, it is exact because the cited standard makes it so — not because we rounded it well.
- 43 CFR Part 3170, Subpart 3174 — Measurement of Oil (§ 3174.2, Definitions)U.S. Bureau of Land Management, via the electronic Code of Federal Regulationshttps://www.ecfr.gov/current/title-43/subtitle-B/chapter-II/subchapter-C/part-3170/subpart-3174Binding federal regulation for oil measurement on federal and Indian leases. Defines a barrel as 42 standard U.S. gallons and sets the base conditions those gallons are referred to: 60 °F and 14.696 psia.
- Energy Glossary — “Barrel”U.S. Energy Information Administrationhttps://www.eia.gov/tools/glossary/index.php?id=bThe U.S. federal energy statistics agency defines the barrel as a unit of volume equal to 42 U.S. gallons. All EIA production, refining and stock series are published on this basis.
- Special Publication 811, Appendix B.8 — Factors for Units Listed AlphabeticallyNational Institute of Standards and Technologyhttps://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8NIST's master table of conversions into SI. Factors printed in boldface are exact by definition rather than measured or rounded — which is how you tell a defined unit from an approximated one.
- Manual of Petroleum Measurement Standards (MPMS) — Ch. 1 “Vocabulary”, Ch. 11.1 “Temperature and Pressure Correction Factors”, Ch. 12.1 “Calculation of Static Petroleum Quantities”American Petroleum Institute (with ASTM D1250 / ISO 91 volume correction tables)Paid standard — cited by designation; obtain from the publisher.The industry standard for turning a gauged tank volume into a traded quantity: observed volume, gross standard volume at 60 °F, and net standard volume after sediment and water. A unit conversion is only the first step of that chain.
Every linked source above was retrieved and checked on 2026-09-02. Factors quoted as exact are exact by definition in the cited document, not rounded by us.