Miles per imperial gallon to US gallons per 100 miles
Type a value in miles per imperial gallon to see it in US gallons per 100 miles straight away, or type in the second box to convert back.
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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 miles per imperial gallon box.
- Read the result in US gallons per 100 miles as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
gal (US)/100 mi = 120.0949926 ÷ mpg (UK)
Divide 120.0949926 by the value in miles per imperial gallon, because the two units are reciprocal.
Example
To convert 25 mpg (UK) to US gallons per 100 miles: 120.0949926 ÷ 25 = 4.8038 gal (US)/100 mi.
Conversion table
| Miles per imperial gallon (mpg (UK)) | US gallons per 100 miles (gal (US)/100 mi) |
|---|---|
| 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
- 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.
- 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.
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 US gallons per 100 miles are in one mile per imperial gallon?
1 mpg (UK) = 120.095 gal (US)/100 mi exactly.
How do I convert miles per imperial gallon to US gallons per 100 miles?
Use gal (US)/100 mi = 120.0949926 ÷ mpg (UK). For example, 25 mpg (UK) = 4.8038 gal (US)/100 mi.
How many miles per imperial gallon are in one US gallon per 100 miles?
1 gal (US)/100 mi = 120.095 mpg (UK).
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.