An imperial gallon is exactly 4.54609 liters.
Imperial gallons to Milliliters Converter — imp gal to mL
Convert Imperial gallon (imp gal) to Milliliter (mL) using the exact conversion factor (1 imperial gallon = 4,546.09 milliliter). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Imperial gallons to Milliliters 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.
Milliliter is 0.001 liter units.
Result = input x 0.00454609 / 1e-6.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Imperial gallons to Milliliters
Imperial gallon and Milliliter 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 typically associated with united Kingdom, Canada (some contexts), and other Commonwealth countries, while Milliliter is typically associated with standard small-volume unit worldwide.
Formula
milliliters = imperial gallons × 4546.09
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 milliliter equals 0.000001 base units, so dividing one by the other gives the direct imperial gallon-to-milliliter factor of 4546.09.
Simple example
1 imp gal × 4546.09 = 4,546.09 mL
1 imperial gallon = 4,546.09 milliliters.
Real-world example
10 imp gal × 4546.09 = 45,460.9 mL
10 imperial gallons = 45,460.9 milliliters.
Conversion table
| Imperial gallon (imp gal) | Milliliter (mL) |
|---|---|
| 1 imp gal | 4,546.09 mL |
| 5 imp gal | 22,730.45 mL |
| 10 imp gal | 45,460.9 mL |
| 25 imp gal | 113,652.25 mL |
| 50 imp gal | 227,304.5 mL |
| 100 imp gal | 454,609 mL |
Reverse conversion: Milliliter to Imperial gallon
1 mL × 0.0002199692483 = 0.0002199692 imp gal
1 milliliter = 0.0002199692 imperial gallons.
imperial gallons = milliliters × 0.000219969248299
For a page dedicated to this direction, see Milliliter to Imperial gallon.
Imperial gallon vs. Milliliter
| Aspect | Imperial gallon | Milliliter |
|---|---|---|
| Family | UK/imperial customary unit | SI derived (metric prefix) unit |
| Typical use | UK fuel and beverage measurement (historically; UK now primarily uses liters for retail) | Medicine dosing (worldwide, including in the US) |
| Where it's used | United Kingdom, Canada (some contexts), and other Commonwealth countries | Standard small-volume unit worldwide |
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 Milliliter
Milliliter (mL) measures volume. A milliliter is one-thousandth of a liter, equal to one cubic centimeter. It is classified as a SI derived (metric prefix) unit.
Where it's used: Standard small-volume unit worldwide
Uses of the Milliliter today
- Medicine dosing (worldwide, including in the US)
- Cooking and recipe measurement outside the US
- Beverage and small-container labeling
History of the Milliliter
The milliliter follows directly from the liter via the 'milli-' SI prefix. It is notable as one of the few metric units in routine US use, since medicine dosing (syringes, liquid medication) is specified in milliliters even in the US.
Historical origin. Milliliter was not the invention of a single named person; it developed through the process described above.
Imperial gallon — sources
- UK Weights and Measures Act 1824 — Establishes the imperial gallon definition.
Milliliter — sources
- BIPM SI Brochure — SI prefixes — Defines 'milli-' as the prefix for 10⁻³.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many milliliters are in 1 imperial gallon?
1 imperial gallon equals 4,546.09 milliliters, using the exact defined conversion factor rather than an estimate.
How do I convert imperial gallon to milliliter?
Multiply the imperial gallon value by 4546.09. The converter above does this instantly to whatever precision you set.
How do I convert milliliter back to imperial gallon?
Use the reverse factor: 1 milliliter equals 0.0002199692 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 milliliter?
Milliliter (mL) measures volume. A milliliter is one-thousandth of a liter, equal to one cubic centimeter. It is classified as a SI derived (metric prefix) unit.
Is the imperial gallon to milliliter 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