Volume conversion
Imperial gallon to US liquid gallon converter
Convert imp gal to gal instantly, choose the displayed precision, and verify the result with the formula and reference table below.
US liquid gallon (gal)
Rounded for display only; calculations retain full precision.
Rounding and precision rules
- Convr calculates first and rounds the displayed result only once, at the final step.
- The default is a maximum of 6 decimal places; trailing zeros are removed.
- Very small values that would appear as zero, and values of 10¹² or more, use scientific notation.
- Display precision is not measurement uncertainty. For scientific, engineering, or regulated work, retain only the digits justified by the source measurement.
Practical context
Understanding this conversion
Imperial gallons occur in UK fuel-economy figures and some older tank or liquid-capacity records. US gallons are used in current American fuel, water, paint, and container specifications.
When comparing fuel economy, converting only the gallon may not be enough if the distance unit also differs. Check the full definition attached to the original figure.
Reviewed August 16, 2026.
Calculation
Imperial gallon to US liquid gallon formula
gal = imp gal × 1.20095
Calculations retain full precision and the result is rounded only for display.
Worked example
For 10 imp gal, the result is 12.009499 gal. Substitute 10 imp gal into the formula to obtain 12.009499 gal.
A numerical value expressed in us liquid gallon is usually larger than the same measurement expressed in imperial gallon, because 1 imp gal equals 1.20095 gal.
Imperial gallon to US liquid gallon reference table
Common values rounded to a maximum of 6 decimal places.
| Imperial gallon (imp gal) | US liquid gallon (gal) |
|---|---|
| 1 imp gal | 1.20095 gal |
| 5 imp gal | 6.00475 gal |
| 10 imp gal | 12.009499 gal |
| 50 imp gal | 60.047496 gal |
| 100 imp gal | 120.094993 gal |
Understanding the units
About Imperial gallon and US liquid gallon
Imperial gallon (imp gal)
One imperial gallon (imp gal) equals 4.54609 L, the base relationship used for this volume conversion.
US liquid gallon (gal)
One us liquid gallon (gal) equals 3.785411784 L, the base relationship used for this volume conversion.
When this conversion is useful
Imperial gallon to US liquid gallon conversion is useful for recipes, beverage quantities, fuel volumes, laboratory measurements, and container capacities. It lets you compare the same volume or capacity across documents, tools, or standards that use different units.
Learn with Convr
Conversion guides
Metric vs Imperial Units: A Practical Comparison
Understand how metric, US customary, and Imperial units differ, where each system is used, and how to convert between them reliably.
Read guide →Everyday conversionsUS Gallons vs Imperial Gallons: What Is the Difference?
Compare US liquid gallons and Imperial gallons, understand their exact liter values, and avoid common fuel and recipe conversion errors.
Read guide →Answers at a glance
Frequently asked questions
How many US gallons are in one Imperial gallon?
One Imperial gallon is approximately 1.200949926 US liquid gallons.
Does gallon conversion affect miles-per-gallon comparisons?
Yes. UK mpg uses the larger Imperial gallon, so the same vehicle can have a higher numerical mpg value than under the US definition.
How does Convr round Imperial gallon to US liquid gallon results?
Convr keeps full numeric precision during the calculation and rounds only the displayed result. The default is a maximum of 6 decimal places, with selectable precision on this page.
Can I convert negative or decimal imperial gallon values?
Yes. The converter accepts positive, negative, decimal, and scientific-notation values. Negative values are physically meaningful for some scales, such as temperature, but not for every measured quantity.
Keep converting