Miles per imperial gallon fuel economy unit.
Miles per imperial gallon to US gallons per 100 miles Converter — mpg imp to gal/100 mi
Convert Miles per imperial gallon (mpg imp) to US gallons per 100 miles (gal/100 mi) using the exact conversion factor (1 miles per imperial gallon = 120.0949926 us gallons per 100 miles). See the formula, worked examples, conversion table, history, and common uses.
Miles per imperial gallon to US gallons per 100 miles converter
Converter
Fuel Economy Converter
Convert MPG, km/L, L/100 km, and related transport fuel economy units.
Context values
Some unit families need one extra value for a physically accurate result.
US gallons per 100 miles fuel economy unit.
Normalize fuel economy to distance per volume, inverting consumption units when needed.
Fuel economy supports both distance-per-volume and volume-per-distance units.
Reserved above the conversion cards and below the converter.
About Converting Miles per imperial gallon to US gallons per 100 miles
Miles per imperial gallon and US gallons per 100 miles are two of the ways the world measures fuel efficiency, and converting between them is essential for comparing a US car's window-sticker rating to a European or Asian one. Miles per imperial gallon is most often used for uk vehicle fuel-economy figures (particularly older or enthusiast/import contexts).
Formula
Fuel economy formulas invert between distance-per-volume and volume-per-distance units as needed.
Efficiency-style units (like mpg or km/L) and consumption-style units (like L/100 km) measure the same underlying thing from opposite directions, so converting between the two families requires a reciprocal, not just a multiplication factor.
Simple example
1 mpg imp × 1.505035e+13 = 120.0949926 gal/100 mi
1 miles per imperial gallon = 120.0949926 us gallons per 100 miles.
Real-world example
30 mpg imp × 1.505035e+13 = 4.003166418 gal/100 mi
30 miles per imperial gallon = 4.003166418 us gallons per 100 miles.
Conversion table
| Miles per imperial gallon (mpg imp) | US gallons per 100 miles (gal/100 mi) |
|---|---|
| 10 mpg imp | 12.00949926 gal/100 mi |
| 20 mpg imp | 6.004749628 gal/100 mi |
| 30 mpg imp | 4.003166418 gal/100 mi |
| 40 mpg imp | 3.002374814 gal/100 mi |
| 50 mpg imp | 2.401899851 gal/100 mi |
| 60 mpg imp | 2.001583209 gal/100 mi |
Reverse conversion: US gallons per 100 miles to Miles per imperial gallon
120.0949926 gal/100 mi × 6.644364e-14 = 0.9999999996 mpg imp
120.0949926 us gallons per 100 miles = 0.9999999996 miles per imperial gallon.
Fuel economy formulas invert between distance-per-volume and volume-per-distance units as needed.
For a page dedicated to this direction, see US gallons per 100 miles to Miles per imperial gallon.
Understanding the Miles per imperial gallon
Miles per imperial gallon (mpg imp) measures fuel economy. Miles per imperial gallon measures distance per imperial gallon (4.54609 L) — about 20% larger than the US gallon, so an imperial MPG figure is correspondingly higher for the same real efficiency. It is classified as a UK/imperial customary unit.
Where it's used: United Kingdom (historically; UK now also uses L/100km)
US mpg vs. imperial mpg. The identical term 'mpg' means a different amount depending on which gallon is used — an imperial mpg figure is about 20% higher than the equivalent US mpg for the same actual fuel efficiency, a common source of confusion when comparing US and UK/Canadian car specs.
Uses of the Miles per imperial gallon today
- UK vehicle fuel-economy figures (particularly older or enthusiast/import contexts)
- Comparing UK-market vehicle specifications to US ones
History of the Miles per imperial gallon
Imperial MPG follows the same automotive tradition as US MPG but uses Britain's imperial gallon (standardized in 1824), leading to the two systems diverging even though they share identical terminology.
Historical origin. Miles per imperial gallon was not the invention of a single named person; it developed through the process described above.
Understanding the US gallons per 100 miles (gal/100 mi)
US gallons per 100 miles fuel economy unit.
Miles per imperial gallon — sources
- UK Department for Transport — Vehicle fuel economy — Historical basis for UK mpg reporting.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many us gallons per 100 miles are in 1 miles per imperial gallon?
1 miles per imperial gallon equals 120.0949926 us gallons per 100 miles, using the exact defined conversion factor rather than an estimate.
How do I convert miles per imperial gallon to us gallons per 100 miles?
Fuel economy units sometimes need inversion rather than simple multiplication — the converter above and the formula section handle this automatically.
How do I convert us gallons per 100 miles back to miles per imperial gallon?
Use the reverse factor: 1 us gallons per 100 miles equals 120.0949926 miles per imperial gallon. You can also use the swap control in the converter above to flip the direction instantly.
What is a miles per imperial gallon?
Miles per imperial gallon (mpg imp) measures fuel economy. Miles per imperial gallon measures distance per imperial gallon (4.54609 L) — about 20% larger than the US gallon, so an imperial MPG figure is correspondingly higher for the same real efficiency. It is classified as a UK/imperial customary unit.
What is a us gallons per 100 miles?
US gallons per 100 miles (gal/100 mi) is a unit of fuel economy.
Is the miles per imperial gallon to us gallons per 100 miles conversion exact?
Yes. Both miles per imperial gallon and us gallons per 100 miles are defined by fixed standards rather than physical artifacts, so the factor of 1.505035e+13 used above is exact to as many digits as you choose to display.
What is the difference between us mpg vs. imperial mpg?
The identical term 'mpg' means a different amount depending on which gallon is used — an imperial mpg figure is about 20% higher than the equivalent US mpg for the same actual fuel efficiency, a common source of confusion when comparing US and UK/Canadian car specs.
Where is the miles per imperial gallon still used today?
United Kingdom (historically; UK now also uses L/100km)