gallons to cubic meters

1 gallon = 0.003785411784 cubic meters, and 1 cubic meter = 264.172 gallons. Every value on this page scales by the same factor: multiply gallons by 0.003785411784. Worked: 100 gallons = 0.37854118 cu m; 1,000 gallons = 3.78541178 cu m.

The US gallon is defined as exactly 231 cubic inches — a definition older than the metric system itself — which means it converts to cubic meters through a chain of exact constants: 231 in³, the 1959 inch of 2.54 cm, and the liter's cubic-decimeter definition. An 8,500-gallon fire truck is 32.18 m³ of water; a 500-gallon fuel tank is 1.89 m³. Every one of those numbers is exact, never rounded, because every step in the chain is a definition.

By EnginStack Editorial Team | Reviewed against NIST, BIPM and primary-source documentation About →
gallons
32.17600016 cubic meters
8,500 gallons = 32.17600016 cubic meters 8,500 cubic meters = 2,245,462.44504426 gallons

Authority: NIST SP 811 (SI usage guide) and the 1959 International Yard and Pound Agreement. The coefficient above is a defined value — it does not come from measurement and carries no uncertainty.

gallons to cubic meters

The gallon's 231 in³ definition dates to the English wine gallon and was fixed by the US in the 19th century; the 1959 agreement then pinned the inch to 2.54 cm exactly. Multiply the chain — 231 × (0.0254)³ — and one US gallon is exactly 0.003785411784 m³. International projects meet this factor at every fuel depot and water tank where an American spec meets a metric one. Note this is the US gallon; the imperial gallon (4.546 L) is a different animal covered elsewhere.

cubic meters = gallons × 0.003785411784
1 US gallon = 0.003785411784 cubic meters — from 231 in³ and the 1959 inch
The factor is exact: 231 × (0.0254)³ m³.

Worked Examples

Example 1: Convert a 500 gallon home heating-oil tank

500 × 0.003785411784 = 1.893 m³

Example 2: Convert a 10,000 gallon fuel store

10,000 × 0.003785411784 = 37.854 m³

Example 3: Convert a 1,000,000 gallon water tower

1,000,000 × 0.003785411784 = 3,785.41 m³

Common gallons to cubic meters Conversions

gallonscubic metersContext
1 gal0.00379 m³One US gallon — 231 cubic inches by definition.
500 gal1.89 m³A home heating-oil tank.
8,500 gal32.2 m³A fire truck's water tank.
10,000 gal37.9 m³A small fuel storage tank.
1,000,000 gal3,785 m³A municipal water tower.

Engineering Context

The cubic meters to gallons page runs the same factor backward. In the volume hub, this is the US-liquid-to-SI bridge: liters to gallons handles the everyday container scale, and gallons to cubic feet the US-internal pair. The fuel-density versions of these numbers appear in the fuel economy family.

The US gallon is defined as exactly 231 cubic inches, a definition older than the metric system, so the conversion to cubic meters runs through the 1959 inch of 2.54 centimeters and comes out exact. One number worth adding to this page is the barrel: a US oil barrel is 42 gallons, which is 0.158987 cubic meters, and this is the unit in which crude is priced while everything downstream is sold by the gallon or the liter. Heating oil and diesel share a density near 0.85 kilograms per liter, so the same tank holds nearly the same mass of either even though the two are priced and taxed differently.

More: m³ to gal · L to gal · gal to ft³ · Volume & Cooking Guide · Volume Hub

Related Unit Converters

cubic meters to gallons Liters to US Gallons Gallons to Cubic Feet Volume & Cooking Conversion Guide Volume Converters

Frequently Asked Questions

How many US gallons are in a cubic meter?

Exactly 264.172052358. The US gallon is 231 in³ = 231 × (0.0254)³ m³ = 0.003785411784 m³, so one cubic meter is the reciprocal: 1 / 0.003785411784 = 264.172052358 gallons.

Why is the US gallon 231 cubic inches?

It descends from the English wine gallon of the 18th century, which was standardized at 231 in³. The US kept that definition when it fixed its units in the 19th century, and it survives today as a legal definition — the British imperial gallon (277.42 in³) went a different way.

Is the imperial gallon the same as the US gallon?

No. The imperial gallon is exactly 4.54609 L, about 20% larger than the US gallon (3.785411784 L). The two share a name and a history but not a volume — always confirm which gallon a spec uses.