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MPG Calculator

Work out the fuel economy you are really getting. Enter the distance driven between fill-ups and the fuel it took to refill, and get miles per gallon along with UK mpg, L/100 km and km/L, plus fuel cost per mile.

Quick examples

Trip meter reading, or the difference between two odometer readings.

The amount it took to refill the tank.

$

Optional, for cost per mile.

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Fuel economy (US mpg)28 mpg
UK (imperial) mpg
33.63 mpg
Liters per 100 km
8.4 L/100 km
Kilometers per liter
11.9 km/L
Fuel cost per mile
$0.125
Fuel cost per kilometer
$0.078

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Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.

    Your recent calculations

    Results you calculate here are kept on this device so you can come back to them.

      Formula

      MPG = miles driven ÷ gallons used
      L/100 km = liters used ÷ kilometers driven × 100
      UK mpg = US mpg × 1.201
      Cost per mile = fill-up cost ÷ miles driven

      How to use it

      1. Fill the tank and reset the trip meter.
      2. Drive normally, then fill up again to the same point.
      3. Enter the trip distance and the amount of fuel the second fill took.
      4. Enter what the fill-up cost if you want cost per mile.

      Worked examples

      350 miles on 12.5 gallons that cost $43.75

      Fuel economy (US mpg)
      28 mpg
      UK (imperial) mpg
      33.63 mpg
      Liters per 100 km
      8.4 L/100 km
      Kilometers per liter
      11.9 km/L
      Fuel cost per mile
      $0.125

      600 km on 45 liters

      Liters per 100 km
      7.5 L/100 km
      Kilometers per liter
      13.33 km/L
      Fuel economy (US mpg)
      31.36 mpg
      UK (imperial) mpg
      37.66 mpg
      Fuel cost per kilometer
      $0.135

      Getting an accurate reading

      Fill to the first automatic click of the pump both times, ideally at the same pump. A single tank can be off by several percent because pumps shut off at slightly different levels, so average three or four tanks for a figure you can trust.

      The car’s own trip computer is often optimistic by a few percent. The fill-up method measures what you actually paid for.

      What is good mpg?

      As rough guides for gasoline vehicles in the US: full-size pickups and large SUVs 15–22 mpg, midsize SUVs 22–28, compact and midsize cars 28–36, and hybrids 40–55. A sudden drop in your own figure is worth investigating: low tire pressure, a dragging brake, or a failing sensor are common causes.

      Questions people ask

      How do I calculate mpg?

      Divide the miles driven by the gallons used. 350 miles on 12.5 gallons is 28 mpg.

      What is 28 mpg in L/100 km?

      8.4 L/100 km. Divide 235.21 by the US mpg figure.

      How do I calculate fuel cost per mile?

      Divide the price per gallon by your mpg. At $3.50 a gallon and 28 mpg, fuel costs 12.5 cents per mile.

      Related calculators

      Fuel Consumption ConverterConvert between US mpg, UK mpg, L/100 km and km/L.Gas Cost CalculatorFuel used and cost for a trip, split between passengers.Cost Per Mile CalculatorThe true cost of driving per mile: fuel plus ownership costs.Commute Cost CalculatorWhat driving to work costs per day, month and year.Trip Time CalculatorDriving time and arrival time from distance, speed and stops.