An imperial gallon is exactly 4.54609 liters.
Imperial gallons to Cubic inches Converter — imp gal to in3
Convert Imperial gallon (imp gal) to Cubic inch (in3) using the exact conversion factor (1 imperial gallon = 277.4194328 cubic inch). See the formula, worked examples, conversion table, history, and common uses.
Imperial gallons to Cubic inches converter
Converter
Volume Converter
Convert metric, US customary, imperial, cooking, dry, and industrial volume units.
Context values
Some unit families need one extra value for a physically accurate result.
A cubic inch is the volume of a one-inch cube.
Result = input x 0.00454609 / 1.6387064e-5.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Imperial gallons to Cubic inches
Imperial gallon and Cubic inch appear side by side at fuel pumps and on beverage labels, since the US measures liquids in gallons while most of the world uses liters. Imperial gallon is most often used for uk fuel and beverage measurement (historically; uk now primarily uses liters for retail).
Formula
cubic inches = imperial gallons × 277.419432792
This factor comes from each unit's defined relationship to the category's base unit: 1 imperial gallon equals 0.00454609 base units, and 1 cubic inch equals 0.000016387064 base units, so dividing one by the other gives the direct imperial gallon-to-cubic inch factor of 277.419432792.
Simple example
1 imp gal × 277.4194328 = 277.4194328 in3
1 imperial gallon = 277.4194328 cubic inches.
Real-world example
10 imp gal × 277.4194328 = 2,774.194328 in3
10 imperial gallons = 2,774.194328 cubic inches.
Conversion table
| Imperial gallon (imp gal) | Cubic inch (in3) |
|---|---|
| 1 imp gal | 277.4194328 in3 |
| 5 imp gal | 1,387.097164 in3 |
| 10 imp gal | 2,774.194328 in3 |
| 25 imp gal | 6,935.48582 in3 |
| 50 imp gal | 13,870.97164 in3 |
| 100 imp gal | 27,741.94328 in3 |
Reverse conversion: Cubic inch to Imperial gallon
277.4194328 in3 × 0.00360465015 = 1 imp gal
277.4194328 cubic inches = 1 imperial gallons.
imperial gallons = cubic inches × 0.00360465014991
For a page dedicated to this direction, see Cubic inch to Imperial gallon.
Understanding the Imperial gallon
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
Where it's used: United Kingdom, Canada (some contexts), and other Commonwealth countries
Imperial gallon vs. US gallon. Britain's 1824 Weights and Measures Act defined a new gallon based on 10 pounds of water, replacing the old wine gallon the US had already adopted — leaving the US (3.785 L) and imperial (4.546 L) gallons about 20% apart today.
Uses of the Imperial gallon today
- UK fuel and beverage measurement (historically; UK now primarily uses liters for retail)
- Commonwealth country liquid measurement in some contexts
History of the Imperial gallon
The imperial gallon was created by Britain's Weights and Measures Act of 1824, defined as the volume of 10 pounds of water, replacing several inconsistent older English gallon definitions (wine gallon, ale gallon, corn gallon) with one standard.
Historical origin. Imperial gallon was not the invention of a single named person; it developed through the process described above.
Understanding the Cubic inch (in3)
A cubic inch is the volume of a one-inch cube.
Imperial gallon — sources
- UK Weights and Measures Act 1824 — Establishes the imperial gallon definition.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many cubic inches are in 1 imperial gallon?
1 imperial gallon equals 277.4194328 cubic inches, using the exact defined conversion factor rather than an estimate.
How do I convert imperial gallon to cubic inch?
Multiply the imperial gallon value by 277.4194328. The converter above does this instantly to whatever precision you set.
How do I convert cubic inch back to imperial gallon?
Use the reverse factor: 1 cubic inch equals 0.0036046502 imperial gallons. You can also use the swap control in the converter above to flip the direction instantly.
What is a imperial gallon?
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
What is a cubic inch?
Cubic inch (in3) is a unit of volume.
Is the imperial gallon to cubic inch conversion exact?
Yes. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between imperial gallon vs. us gallon?
Britain's 1824 Weights and Measures Act defined a new gallon based on 10 pounds of water, replacing the old wine gallon the US had already adopted — leaving the US (3.785 L) and imperial (4.546 L) gallons about 20% apart today.
Where is the imperial gallon still used today?
United Kingdom, Canada (some contexts), and other Commonwealth countries