Gal/100 Mi (US) to MPG (US) (gal/100 mi to mpg (US))
1 gallon (US) per 100 miles equals 100 miles per gallon (US).
How to convert gallons (US) per 100 miles to miles per gallon (US)
Converting gallons (US) per 100 miles to miles per gallon (US) is not a simple multiplication, so use the formula below.
miles per gallon (US) = 100 ÷ gallons (US) per 100 miles
Example: 10 gallons (US) per 100 miles = 10 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 (US) Per 100 Miles (gal/100 mi)
US gallons used per 100 miles. Proposed in the US as a more intuitive way to compare efficiency than miles per gallon.
Gallons per 100 miles flips the familiar miles-per-gallon figure upside down, so that lower numbers mean a more efficient vehicle. New US window stickers have shown it next to mpg since the EPA's 2011 labeling rule, which became mandatory for model year 2013. The label estimates how much fuel or electricity a car needs to cover 100 miles.
The reason is the so-called MPG illusion. Fuel use per mile is the reciprocal of mpg, so equal gains in mpg do not save equal fuel. Lifting a car from 10 to 20 mpg doubles its efficiency, while lifting another from 50 to 60 mpg improves it by only 20 percent, even though each gains 10 mpg.
The unit is the same measure as liters per 100 kilometers used in much of the world. One gallon per 100 miles equals about 2.352 L per 100 km, and the converter stores it as kilometers per liter, so a value x gal/100 mi corresponds to 42.514 divided by x km/L. That is also why a reading of zero has no meaning.
1 gallon (US) per 100 miles = 42.51437074 kilometers per liter (approximately).
Sources: Wikipedia: Fuel economy in automobiles; Wikipedia: Fuel efficiency
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 (US) (reverse)
- Gal/100 mi (US) to km/L
- Gal/100 mi (US) to MPG (UK)
- Gal/100 mi (US) 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 (UK) to MPG (US)
- L/mil to MPG (US)
See all fuel economy units.