US gallons per 100 miles to miles per imperial gallon
Type a value in US gallons per 100 miles to see it in miles per imperial gallon straight away, or type in the second box to convert back.
Loading the tool…
Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the US gallons per 100 miles box.
- Read the result in miles per imperial gallon as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
mpg (UK) = 120.0949926 ÷ gal (US)/100 mi
Divide 120.0949926 by the value in US gallons per 100 miles, because the two units are reciprocal.
Example
To convert 25 gal (US)/100 mi to miles per imperial gallon: 120.0949926 ÷ 25 = 4.8038 mpg (UK).
Conversion table
| US gallons per 100 miles (gal (US)/100 mi) | Miles per imperial gallon (mpg (UK)) |
|---|---|
| 1 | 120.095 |
| 2 | 60.0475 |
| 3 | 40.0317 |
| 5 | 24.019 |
| 10 | 12.0095 |
| 20 | 6.00475 |
| 25 | 4.8038 |
| 50 | 2.4019 |
| 100 | 1.20095 |
| 250 | 0.48038 |
| 500 | 0.24019 |
| 1,000 | 0.120095 |
About the units
- US gallon per 100 miles
- US gallons used to travel 100 miles, shown on US fuel economy labels. It equals 100 divided by US mpg.
- Mile per imperial gallon
- Miles per imperial gallon of 4.54609 liters, used in the United Kingdom. It reads higher than US mpg for the same car because the gallon is larger.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many miles per imperial gallon are in one US gallon per 100 miles?
1 gal (US)/100 mi = 120.095 mpg (UK) exactly.
How do I convert US gallons per 100 miles to miles per imperial gallon?
Use mpg (UK) = 120.0949926 ÷ gal (US)/100 mi. For example, 25 gal (US)/100 mi = 4.8038 mpg (UK).
How many US gallons per 100 miles are in one mile per imperial gallon?
1 mpg (UK) = 120.095 gal (US)/100 mi.
Why is mpg to L/100 km not a simple multiplication?
The units are reciprocal: one is distance per fuel, the other fuel per distance. You divide about 235.215 by the US mpg value, so 30 mpg is about 7.84 L/100 km.
Why do US and UK mpg differ?
The imperial gallon is 4.54609 L and the US gallon is 3.785411784 L, so the same car shows about 20% more miles per gallon in UK figures.