Convert US gallons to Imperial gallons
1 US gallon is 0.83 gal (UK). One US gallon is exactly 0.832674184629 imperial gallons.
One US gallon is 0.83267418 imperial gallons. To convert US gallons to imperial gallons, multiply by 0.83267418; to go the other way, divide by 0.83267418 or multiply by 1.2009499. The relation is exact but the figure is not: it is a rounding of a number that does not terminate, and it follows from NIST Handbook 130. Exactly 231 cubic inches.
Factor checked against the defining standard · How we check
- US gallons × 0.83267418
1 * 0.83267420.833 gal (UK)
1 US gallon in every volume unit
| Unit | Value | Exact factor |
|---|---|---|
| US teaspoons | 768 tsp | × 768 |
| US tablespoons | 256 tbsp | × 256 |
| US fluid ounces | 128 fl oz | × 128 |
| US cups | 16 cup | × 16 |
| US pints | 8 pt | × 8 |
| US quarts | 4 qt | × 4 |
| US gallons (as entered) | 1 gal | — |
| milliliters | 3,785.411784 ml | × 3,785.411784 |
| liters | 3.785411784 L | × 3.785411784 |
| imperial gallons | 0.8326741846 gal (UK) | × 0.832674184629 |
| imperial quarts | 3.330696739 qt (UK) | × 3.33069673852 |
| imperial pints | 6.661393477 pt (UK) | × 6.66139347703 |
| imperial fluid ounces | 133.2278695 fl oz (UK) | × 133.227869541 |
| imperial gills | 26.64557391 gi (UK) | × 26.6455739081 |
| cubic millimetres | 3,785,411.784 mm³ | × 3,785,411.784 |
| cubic centimetres | 3,785.411784 cm³ | × 3,785.411784 |
| cubic inches | 231 in³ | × 231 |
| cubic feet | 0.1336805556 ft³ | × 0.133680555556 |
| cubic yards | 0.004951131687 yd³ | × 0.00495113168724 |
| cubic metres | 0.003785411784 m³ | × 0.003785411784 |
Factors are entered by hand from NIST Handbook 130 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert US gallons to imperial gallons? The converter and the working
- 1.Take the measurement in US gallons.
- 2.Multiply by 0.83267418 — that is how many imperial gallons fit in one US gallon.
- 3.To go back the other way, divide by 0.83267418, or multiply by 1.2009499.
Worked example: 25 US gallons to imperial gallons
- Formula
- gal × 0.83267418 = gal (UK)
- Arithmetic
- 25 × 0.83267418 = 20.82 gal (UK)
- Answer
- 25 gal = 20.82 gal (UK)
The factor is rounded for display; the figure above is computed from the full value.
US gallons to imperial gallons conversion table
| US gallons | Imperial gallons |
|---|---|
| 1 gal | 0.83 gal (UK) |
| 2 gal | 1.67 gal (UK) |
| 3 gal | 2.5 gal (UK) |
| 4 gal | 3.33 gal (UK) |
| 5 gal | 4.16 gal (UK) |
| 6 gal | 5 gal (UK) |
| 7 gal | 5.83 gal (UK) |
| 8 gal | 6.66 gal (UK) |
| 9 gal | 7.49 gal (UK) |
| 10 gal | 8.33 gal (UK) |
| 12 gal | 9.99 gal (UK) |
| 15 gal | 12.49 gal (UK) |
| 20 gal | 16.65 gal (UK) |
| 25 gal | 20.82 gal (UK) |
| 50 gal | 41.63 gal (UK) |
| 100 gal | 83.27 gal (UK) |
| 200 gal | 166.53 gal (UK) |
| 300 gal | 249.8 gal (UK) |
| 500 gal | 416.34 gal (UK) |
| 1000 gal | 832.67 gal (UK) |
| 2000 gal | 1,665.35 gal (UK) |
| 5000 gal | 4,163.37 gal (UK) |
| 10000 gal | 8,326.74 gal (UK) |
The two gallons differ by 20%, which is why mpg figures do not compare
An imperial gallon is 4.54609 liters exactly; a US gallon is 3.785411784. A British car doing 40 mpg is doing about 33 US mpg on the same fuel, and a US car rated 30 mpg would be advertised as 36 in the UK. Neither country converts the figure when quoting the other’s, which is how the same engine ends up with two economy numbers that look like a mistake.
NIST Handbook 44, Appendix C — general tables of units of measurement
What is a US gallon?
Exactly 231 cubic inches. The imperial gallon is 4.546 liters, so US and UK fuel economy figures are not comparable.
What is an imperial gallon?
Exactly 4.54609 liters since 1985, and the reason UK and US fuel economy figures cannot be compared: it is 20% larger than the US gallon, so 40 mpg in Britain is about 33 mpg in America on the same car.
How many imperial gallons are in a US gallon?
One US gallon is 0.83267418 imperial gallons. Going the other way, one imperial gallon is 1.2009499 US gallons. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every volume unit here
The whole group — 20 units with their symbols and the size of each one in liters — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a US gallon.
Cite this page
- APA
- Rule Calculator. (2026). Convert US gallons to imperial gallons. Rule Calculator. https://rulecalculators.com/convert/gallon-to-imperial-gallon
- MLA
- "Convert US gallons to imperial gallons." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/gallon-to-imperial-gallon.
- Chicago
- Rule Calculator. "Convert US gallons to imperial gallons." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/gallon-to-imperial-gallon.
The date is when the figures on this page were last checked against their source, not the day you opened it. Add your own access date if your style needs one.
Questions people actually ask
- How many imperial gallons are in a US gallon?
- 0.83267418. Exactly 4.54609 liters since 1985, and the reason UK and US fuel economy figures cannot be compared: it is 20% larger than the US gallon, so 40 mpg in Britain is about 33 mpg in America on the same car.
- How do I convert imperial gallons back to US gallons?
- Divide by 0.83267418, or multiply by 1.2009499 — they are the same operation.
Other volume conversions
Imperial gallons to US gallons — the same conversion the other way.