The formula
US gal = L × 0.2641720524
Where the factor comes from — each unit by its definition, then its size in SI:
1 L = m³ / 1000 = 0.001 m³1 US gal = 231 × in³ = 0.003785411784 m³
Dividing the two SI sizes gives the factor: 0.264172052358 (rounded for display; the underlying ratio is fixed by the definitions). The reverse factor is 3.785411784.
The cubic metre is the SI unit of volume; the litre is exactly one thousandth of it. The US and UK gallons are different sizes, which is why a fuel-economy figure in mpg depends on which country printed it.
Worked examples
- A soft-drink bottle: 2 L = 0.528344 US gal — 2 × 0.2641720524 = 0.528344
- A paint bucket: 18.9271 L = 5 US gal — 18.9271 × 0.2641720524 = 5
- A water tank (1 m³): 1,000 L = 264.172 US gal — 1,000 × 0.2641720524 = 264.172
- A drinks can (330 mL): 0.33 L = 0.0871768 US gal — 0.33 × 0.2641720524 = 0.0871768
Frequently asked questions
How many US gallons is 1 L?
1 L = 0.264172052358 US gal.
How do I convert US gallons back to litres?
Divide by 0.264172052358 — or multiply by 3.785411784: 1 US gal = 3.785411784 L.