Convert Cubic millimetres to Imperial gallons
1 cubic millimetre is 2.20e-7 gal (UK). One cubic millimetre is exactly 2.19969248299e-7 imperial gallons.
One cubic millimetre is 2.1997 × 10^-7 imperial gallons. To convert cubic millimetres to imperial gallons, multiply by 2.1997 × 10^-7; to go the other way, divide by 2.1997 × 10^-7 or multiply by 4546090. 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. A millionth of a litre, because the millimetre is a thousandth of a metre and volume cubes the factor.
Factor checked against the defining standard · How we check
- Cubic millimetres × 2.1997 × 10^-7
1 * 0.00000020 gal (UK)
1 cubic millimetre in every volume unit
| Unit | Value | Exact factor |
|---|---|---|
| US teaspoons | 0.0002028841362 tsp | × 0.000202884136211 |
| US tablespoons | 0.0000676280454 tbsp | × 0.0000676280454037 |
| US fluid ounces | 0.0000338140227 fl oz | × 0.0000338140227018 |
| US cups | 0.000004226752838 cup | × 0.00000422675283773 |
| US pints | 0.000002113376419 pt | × 0.00000211337641887 |
| US quarts | 0.000001056688209 qt | × 0.00000105668820943 |
| US gallons | 0.0000002641720524 gal | × 0.000000264172052358 |
| milliliters | 0.001 ml | × 0.001 |
| liters | 0.000001 L | × 0.000001 |
| imperial gallons | 0.0000002199692483 gal (UK) | × 0.000000219969248299 |
| imperial quarts | 0.0000008798769932 qt (UK) | × 0.000000879876993196 |
| imperial pints | 0.000001759753986 pt (UK) | × 0.00000175975398639 |
| imperial fluid ounces | 0.00003519507973 fl oz (UK) | × 0.0000351950797279 |
| imperial gills | 0.000007039015946 gi (UK) | × 0.00000703901594557 |
| cubic millimetres (as entered) | 1 mm³ | — |
| cubic centimetres | 0.001 cm³ | × 0.001 |
| cubic inches | 0.00006102374409 in³ | × 0.0000610237440947 |
| cubic feet | 0.00000003531466672 ft³ | × 0.0000000353146667215 |
| cubic yards | 0.000000001307950619 yd³ | × 0.00000000130795061931 |
| cubic metres | 0.000000001 m³ | × 0.000000001 |
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 millimetres to imperial gallons? The converter and the working
- 1.Take the measurement in cubic millimetres.
- 2.Multiply by 2.1997 × 10^-7 — that is how many imperial gallons fit in one cubic millimetre.
- 3.To go back the other way, divide by 2.1997 × 10^-7, or multiply by 4546090.
Worked example: 25 cubic millimetres to imperial gallons
- Formula
- mm³ × 2.1997 × 10^-7 = gal (UK)
- Arithmetic
- 25 × 2.1997 × 10^-7 = 0.000005499 gal (UK)
- Answer
- 25 mm³ = 0.000005499 gal (UK)
The factor is rounded for display; the figure above is computed from the full value.
Cubic millimetres to imperial gallons conversion table
| Cubic millimetres | Imperial gallons |
|---|---|
| 1 mm³ | 2.20e-7 gal (UK) |
| 2 mm³ | 4.40e-7 gal (UK) |
| 3 mm³ | 6.60e-7 gal (UK) |
| 4 mm³ | 8.80e-7 gal (UK) |
| 5 mm³ | 0.0000011 gal (UK) |
| 6 mm³ | 0.00000132 gal (UK) |
| 7 mm³ | 0.00000154 gal (UK) |
| 8 mm³ | 0.00000176 gal (UK) |
| 9 mm³ | 0.00000198 gal (UK) |
| 10 mm³ | 0.0000022 gal (UK) |
| 12 mm³ | 0.00000264 gal (UK) |
| 15 mm³ | 0.0000033 gal (UK) |
| 20 mm³ | 0.000004399 gal (UK) |
| 25 mm³ | 0.000005499 gal (UK) |
| 50 mm³ | 0.000011 gal (UK) |
| 100 mm³ | 0.000022 gal (UK) |
| 200 mm³ | 0.00004399 gal (UK) |
| 300 mm³ | 0.00006599 gal (UK) |
| 500 mm³ | 0.00011 gal (UK) |
| 1000 mm³ | 0.00022 gal (UK) |
| 2000 mm³ | 0.0004399 gal (UK) |
| 5000 mm³ | 0.0011 gal (UK) |
| 10000 mm³ | 0.0022 gal (UK) |
What is a cubic millimetre?
A millionth of a litre, because the millimetre is a thousandth of a metre and volume cubes the factor. A microlitre by another name, and the unit injection-moulding shot sizes are quoted in.
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 millimetre?
One cubic millimetre is 2.1997 × 10^-7 imperial gallons. Going the other way, one imperial gallon is 4546090 cubic millimetres. 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 millimetre.
Cite this page
- APA
- Rule Calculator. (2026). Convert Cubic millimetres to imperial gallons. Rule Calculator. https://rulecalculators.com/convert/cubic-millimeter-to-imperial-gallon
- MLA
- "Convert Cubic millimetres to imperial gallons." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/cubic-millimeter-to-imperial-gallon.
- Chicago
- Rule Calculator. "Convert Cubic millimetres to imperial gallons." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/cubic-millimeter-to-imperial-gallon.
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Questions people actually ask
- How many imperial gallons are in a cubic millimetre?
- 2.1997 × 10^-7. 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 millimetres?
- Divide by 2.1997 × 10^-7, or multiply by 4546090 — they are the same operation.
Other volume conversions
Imperial gallons to cubic millimetres — the same conversion the other way.