Convert Cubic inches to Imperial gallons
1 cubic inch is 0.003605 gal (UK). One cubic inch is exactly 0.00360465014991 imperial gallons.
One cubic inch is 0.0036046501 imperial gallons. To convert cubic inches to imperial gallons, multiply by 0.0036046501; to go the other way, divide by 0.0036046501 or multiply by 277.41943. 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 16.387064 millilitres, since the inch is exactly 25.4 mm.
Factor checked against the defining standard · How we check
- Cubic inches × 0.0036046501
1 * 0.00360470.004 gal (UK)
1 cubic inch in every volume unit
| Unit | Value | Exact factor |
|---|---|---|
| US teaspoons | 3.324675325 tsp | × 3.32467532468 |
| US tablespoons | 1.108225108 tbsp | × 1.10822510823 |
| US fluid ounces | 0.5541125541 fl oz | × 0.554112554113 |
| US cups | 0.06926406926 cup | × 0.0692640692641 |
| US pints | 0.03463203463 pt | × 0.034632034632 |
| US quarts | 0.01731601732 qt | × 0.017316017316 |
| US gallons | 0.004329004329 gal | × 0.004329004329 |
| milliliters | 16.387064 ml | × 16.387064 |
| liters | 0.016387064 L | × 0.016387064 |
| imperial gallons | 0.00360465015 gal (UK) | × 0.00360465014991 |
| imperial quarts | 0.0144186006 qt (UK) | × 0.0144186005996 |
| imperial pints | 0.0288372012 pt (UK) | × 0.0288372011993 |
| imperial fluid ounces | 0.576744024 fl oz (UK) | × 0.576744023985 |
| imperial gills | 0.1153488048 gi (UK) | × 0.115348804797 |
| cubic millimetres | 16,387.064 mm³ | × 16,387.064 |
| cubic centimetres | 16.387064 cm³ | × 16.387064 |
| cubic inches (as entered) | 1 in³ | — |
| cubic feet | 0.0005787037037 ft³ | × 0.000578703703704 |
| cubic yards | 0.00002143347051 yd³ | × 0.0000214334705075 |
| cubic metres | 0.000016387064 m³ | × 0.000016387064 |
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 cubic inches to imperial gallons? The converter and the working
- 1.Take the measurement in cubic inches.
- 2.Multiply by 0.0036046501 — that is how many imperial gallons fit in one cubic inch.
- 3.To go back the other way, divide by 0.0036046501, or multiply by 277.41943.
Worked example: 25 cubic inches to imperial gallons
- Formula
- in³ × 0.0036046501 = gal (UK)
- Arithmetic
- 25 × 0.0036046501 = 0.09 gal (UK)
- Answer
- 25 in³ = 0.09 gal (UK)
The factor is rounded for display; the figure above is computed from the full value.
Cubic inches to imperial gallons conversion table
| Cubic inches | Imperial gallons |
|---|---|
| 1 in³ | 0.003605 gal (UK) |
| 2 in³ | 0.01 gal (UK) |
| 3 in³ | 0.01 gal (UK) |
| 4 in³ | 0.01 gal (UK) |
| 5 in³ | 0.02 gal (UK) |
| 6 in³ | 0.02 gal (UK) |
| 7 in³ | 0.03 gal (UK) |
| 8 in³ | 0.03 gal (UK) |
| 9 in³ | 0.03 gal (UK) |
| 10 in³ | 0.04 gal (UK) |
| 12 in³ | 0.04 gal (UK) |
| 15 in³ | 0.05 gal (UK) |
| 20 in³ | 0.07 gal (UK) |
| 25 in³ | 0.09 gal (UK) |
| 50 in³ | 0.18 gal (UK) |
| 100 in³ | 0.36 gal (UK) |
| 200 in³ | 0.72 gal (UK) |
| 300 in³ | 1.08 gal (UK) |
| 500 in³ | 1.8 gal (UK) |
| 1000 in³ | 3.6 gal (UK) |
| 2000 in³ | 7.21 gal (UK) |
| 5000 in³ | 18.02 gal (UK) |
| 10000 in³ | 36.05 gal (UK) |
What is a cubic inch?
Exactly 16.387064 millilitres, since the inch is exactly 25.4 mm. American engine displacement was quoted in it until the 1980s — a 350 small block is 5.7 litres.
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 cubic inch?
One cubic inch is 0.0036046501 imperial gallons. Going the other way, one imperial gallon is 277.41943 cubic inches. 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 cubic inch.
Cite this page
- APA
- Rule Calculator. (2026). Convert Cubic inches to imperial gallons. Rule Calculator. https://rulecalculators.com/convert/cubic-inch-to-imperial-gallon
- MLA
- "Convert Cubic inches to imperial gallons." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/cubic-inch-to-imperial-gallon.
- Chicago
- Rule Calculator. "Convert Cubic inches to imperial gallons." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/cubic-inch-to-imperial-gallon.
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Questions people actually ask
- How many imperial gallons are in a cubic inch?
- 0.0036046501. 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 cubic inches?
- Divide by 0.0036046501, or multiply by 277.41943 — they are the same operation.
Other volume conversions
Imperial gallons to cubic inches — the same conversion the other way.