Gal/100 Mi (UK) to MPG (US)
1 gallon (imperial) per 100 miles equals 83.26741846 miles per gallon (US).
How to convert gallons (imperial) per 100 miles to miles per gallon (US)
Converting gallons (imperial) per 100 miles to miles per gallon (US) is not a simple multiplication, so use the formula below.
miles per gallon (US) = 83.26741846 ÷ gallons (imperial) per 100 miles
Example: 10 gallons (imperial) per 100 miles = 8.326741846 miles per gallon (US).
Miles per gallon rises as a car gets more efficient, while liters per 100 km falls. The conversion between them is a reciprocal (for US mpg: L/100 km = 235.215 ÷ mpg).
About these units
Gallon (imperial) Per 100 Miles (gal/100 mi (UK))
Imperial gallons used per 100 miles.
Most fuel-economy figures rise when a car gets better, which is why miles per gallon can mislead: going from 10 to 20 miles per gallon saves far more fuel than going from 50 to 60. Quoting consumption per fixed distance avoids that trap, and the United States adopted the idea on its fuel-economy window stickers, which show US gallons per 100 miles. Using imperial gallons of 4.54609 liters gives a British-flavored variant of the same idea, equivalent in spirit to liters per 100 kilometers.
Because lower numbers mean better efficiency, the relationship with distance-per-volume units is a reciprocal. In this converter, kilometers per liter equals 35.4006 divided by the number of imperial gallons per 100 miles, since 100 miles is 160.9344 kilometers and a gallon is 4.54609 liters. For example, 5 gallons per 100 miles is about 7.08 kilometers per liter, or 20 miles per imperial gallon. The unit is rare in practice, and the British continue to rely on miles per imperial gallon alongside liters per 100 kilometers.
1 gallon (imperial) per 100 miles = 35.40061899 kilometers per liter (approximately).
Sources: Wikipedia: Fuel economy in automobiles; NIST SP 811, Appendix B.8 conversion factors
Mile Per Gallon (US) (mpg (US))
Miles traveled on one US gallon of fuel. The standard fuel-economy unit in the United States; higher is better.
American fuel economy became a matter of policy in the 1970s. After the 1973 Arab oil embargo, Congress enacted the Corporate Average Fuel Economy rules in 1975, setting a sales-weighted average for each manufacturer's cars and light trucks. Fleet economy had been sliding until 1973, reaching a low of about 13.4 mpg, then rose as fuel costs rose: about 17 mpg in 1978, 22 in 1982, and about 25.4 mpg for the average new vehicle in the 2020 model year. Earlier still, the Mobil Economy Run (1936 to 1968) tested real-world mileage on a coast-to-coast route.
The US gallon is legally 231 cubic inches, or 3.785411784 litres. It descends from the English wine gallon, redefined as 231 cubic inches in 1706 under Queen Anne and adopted as the US standard in 1836. It is about 17 percent smaller than the imperial gallon, so US mpg figures look lower than British ones for the same car. Mpg has a quirk known as the MPG illusion: going from 10 to 20 mpg halves fuel use, but going from 50 to 60 mpg saves far less, even though both are 10 mpg gains. For that reason the EPA label also shows gallons per 100 miles.
1 mile per gallon (US) = 0.4251437074 kilometers per liter (approximately).
Sources: Wikipedia: Fuel economy in automobiles; Wikipedia: Imperial gallon; fueleconomy.gov: Learn more about the gasoline label
Related conversions
- MPG (US) to gal/100 mi (UK) (reverse)
- Gal/100 mi (UK) to km/L
- Gal/100 mi (UK) to MPG (UK)
- Gal/100 mi (UK) to L/100 km
- Km/L to MPG (US)
- MPG (UK) to MPG (US)
- L/100 km to MPG (US)
- Mi/L to MPG (US)
- Gal/100 mi (US) to MPG (US)
- L/mil to MPG (US)
See all fuel economy units.