An imperial gallon is exactly 4.54609 liters.
Imperial gallons to Cubic Decimeters Converter — imp gal to dm3
Convert Imperial gallon (imp gal) to Cubic Decimeter (dm3) using the exact conversion factor (1 imperial gallon = 4.54609 cubic decimeter). See the formula, worked examples, conversion table, history, and common uses.
Imperial gallons to Cubic Decimeters 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.
Cubic metric volume unit.
Result = input x 0.00454609 / 0.001.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Imperial gallons to Cubic Decimeters
Imperial gallon and Cubic Decimeter 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 decimeters = imperial gallons × 4.54609
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 decimeter equals 0.001 base units, so dividing one by the other gives the direct imperial gallon-to-cubic decimeter factor of 4.54609.
Simple example
1 imp gal × 4.54609 = 4.54609 dm3
1 imperial gallon = 4.54609 cubic decimeters.
Real-world example
10 imp gal × 4.54609 = 45.4609 dm3
10 imperial gallons = 45.4609 cubic decimeters.
Conversion table
| Imperial gallon (imp gal) | Cubic Decimeter (dm3) |
|---|---|
| 1 imp gal | 4.54609 dm3 |
| 5 imp gal | 22.73045 dm3 |
| 10 imp gal | 45.4609 dm3 |
| 25 imp gal | 113.65225 dm3 |
| 50 imp gal | 227.3045 dm3 |
| 100 imp gal | 454.609 dm3 |
Reverse conversion: Cubic Decimeter to Imperial gallon
4.54609 dm3 × 0.2199692483 = 1 imp gal
4.54609 cubic decimeters = 1 imperial gallons.
imperial gallons = cubic decimeters × 0.219969248299
For a page dedicated to this direction, see Cubic Decimeter 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 Decimeter (dm3)
Cubic metric volume unit.
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 decimeters are in 1 imperial gallon?
1 imperial gallon equals 4.54609 cubic decimeters, using the exact defined conversion factor rather than an estimate.
How do I convert imperial gallon to cubic decimeter?
Multiply the imperial gallon value by 4.54609. The converter above does this instantly to whatever precision you set.
How do I convert cubic decimeter back to imperial gallon?
Use the reverse factor: 1 cubic decimeter equals 0.2199692483 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 decimeter?
Cubic Decimeter (dm3) is a unit of volume.
Is the imperial gallon to cubic decimeter 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