Mileage Calculator

1. Fill your tank completely. Note your odometer reading at this point (starting odometer).
2. Drive normally until you need to refuel. At the next fill-up, note your new odometer reading (ending odometer).
3. Fill up completely again. Note exactly how many gallons it took to fill up. This is the gallons used for the miles you just drove.
4. Enter both odometer readings and gallons into the calculator. Your MPG, L/100km, and (optionally) cost per mile appear instantly.
5. For trip cost: Enter your destination's distance, your vehicle's MPG, and the current gas price to see how much fuel will cost for the trip.

For the most accurate reading, always use the full-tank method described above. Partial fills give misleading results.

MPG = Miles Driven / Gallons Used

Miles Driven = Ending Odometer - Starting Odometer

L/100km = 235.215 / MPG
(because 1 US gallon = 3.78541 L, 1 mile = 1.60934 km)

Cost per mile = Gas Price per Gallon / MPG

Annual fuel cost = Cost per mile × Annual Miles Driven

Trip fuel cost = Trip Distance / MPG × Gas Price

The L/100km metric is the standard in most countries outside the US. Lower L/100km means better fuel economy (the inverse of MPG). A vehicle getting 30 MPG uses 7.84 L/100km.

Annual cost assumes 12,000 miles per year, which is close to the US average of about 11,500 to 13,500 miles per year according to the Federal Highway Administration.