Convert Imperial Gallons to Cubic Inches
1 imperial gallon (gal (imp)) equals 277.4194328 cubic inches (in³).
1 gal (imp) = 277.4194328 in³
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk imperial gallon to cubic inch converter to paste a column from Excel.
How to Convert Imperial Gallon to Cubic Inch
- 1 gal (imp) = 277.4194328 in³
- 1 in³ = 0.00360465015 gal (imp)
- Example: convert 15 gal (imp) to in³: 15 gal (imp) = 15 × 277.4194328 in³ = 4161.291492 in³
Formula
in³ = gal (imp) × 277.4194327916
Derivation from SI units:
- 1 imp gal = 4.54609 L = 0.00454609 m³ (exact, by definition)
- 1 in³ = (0.0254 m)³ = 1.6387064 × 10⁻⁵ m³ = 16.387064 cm³
- 1 gal (imp) = 0.00454609 m³ ÷ 0.000016387064 m³ per in³ = 277.4194327916 in³
Both units are defined exactly, so the factor is exact. Imperial Gallon definition: imperial gallon; Cubic Inch definition: cubic inch.
Worked examples
- A reading of 5 gal (imp) converts to 1387.097164 in³.
5 gal (imp) × 277.4194328 = 1387.097164 in³ - A value of 25 gal (imp) is 6935.48582 in³.
25 gal (imp) × 277.4194328 = 6935.48582 in³
Imperial Gallon to Cubic Inch conversion table
| Imperial Gallons (gal (imp)) | Cubic Inches (in³) |
|---|---|
| 0.25 gal (imp) | 69.3548582 in³ |
| 0.5 gal (imp) | 138.7097164 in³ |
| 1 gal (imp) | 277.4194328 in³ |
| 2 gal (imp) | 554.8388656 in³ |
| 5 gal (imp) | 1387.097164 in³ |
| 10 gal (imp) | 2774.194328 in³ |
| 15 gal (imp) | 4161.291492 in³ |
| 20 gal (imp) | 5548.388656 in³ |
| 25 gal (imp) | 6935.48582 in³ |
| 40 gal (imp) | 11096.77731 in³ |
| 50 gal (imp) | 13870.97164 in³ |
| 100 gal (imp) | 27741.94328 in³ |
| 1000 gal (imp) | 277419.4328 in³ |
Where it's used
Imperial Gallons are used for fuel economy in the UK (miles per gallon), while cubic inches appear in US engine displacement (e.g. 350 cubic inches ≈ 5.7 L). Both measure volume (capacity), so the conversion is a fixed factor.
Imperial Gallon to other volume units
| Conversion | 1 gal (imp) equals |
|---|---|
| imperial gallon to cubic meter | 0.00454609 m³ |
| imperial gallon to liter | 4.54609 L |
| imperial gallon to milliliter | 4546.09 mL |
| imperial gallon to cubic centimeter | 4546.09 cm³ |
| imperial gallon to cubic foot | 0.1605436532 ft³ |
| imperial gallon to cubic inch | 277.4194328 in³ |
| imperial gallon to US gallon | 1.200949926 gal (US) |
Frequently asked questions
How many cubic inches are in 1 imperial gallon?
1 gal (imp) = 277.4194328 in³.
How do I convert imperial gallons to cubic inches?
Multiply the value in gal (imp) by 277.4194328. For example, 15 gal (imp) × 277.4194328 = 4161.291492 in³.
Is the gal (imp) to in³ conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "gallon [Canadian and U.K. (Imperial)]".
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "cubic inch (in³)".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Imperial Gallons to Cubic Inches. Retrieved October 17, 2026, from https://scientificconverters.com/volume/imperial-gallons-to-cubic-inches/
IEEE
Scientific Converters, "Convert Imperial Gallons to Cubic Inches," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/volume/imperial-gallons-to-cubic-inches/