Fuel Mileage Calculator

Work out your vehicle's fuel economy in miles per gallon (MPG) from distance driven and fuel used, then estimate cost per mile and the fuel and cost needed for a future trip.

Quick Facts

Formula
MPG = Distance driven ÷ Fuel used
Cost per mile = Price per gallon ÷ MPG.

Your Results

Calculated
Fuel Economy
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Miles per gallon (MPG)
Cost per Mile
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Fuel cost per mile driven
Fuel for Trip
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Gallons needed for the planned distance
Trip Fuel Cost
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Estimated cost for the planned distance

Ready

Enter your distance, fuel used, price per gallon, and a planned trip distance, then press Calculate.

Understanding the Fuel Mileage Calculator

This tool measures your vehicle's fuel economy using the standard miles-per-gallon (MPG) formula, then applies that figure to money and trip planning. Enter the miles you drove and the gallons of fuel it took to drive them, and the calculator works out your MPG, your cost per mile, and how much fuel and money a future trip of any length will require.

The formulas

Four values come directly from your inputs, using standard, well-established relationships:

  • Fuel economy (MPG): MPG = Distance driven ÷ Fuel used. Driving 300 miles on 12 gallons gives 300 ÷ 12 = 25 MPG.
  • Cost per mile: Cost per mile = Price per gallon ÷ MPG. At $3.50 per gallon and 25 MPG, that is $3.50 ÷ 25 = $0.14 per mile.
  • Fuel needed for a trip: Fuel needed = Trip distance ÷ MPG. A 500-mile trip at 25 MPG needs 500 ÷ 25 = 20 gallons.
  • Trip fuel cost: Trip cost = Fuel needed × Price per gallon. Twenty gallons at $3.50 comes to $70.00.

Measuring fuel used accurately

The most reliable way to find "fuel used" is the fill-up method: fill your tank completely and reset (or note) your trip odometer, drive normally for a while, then fill the tank again. The gallons required to refill the tank is the fuel used, and the miles shown on your trip odometer since the first fill-up is the distance driven. Using a full-to-full fill-up avoids errors from a partially filled tank.

Practical context

MPG varies with driving conditions — highway cruising, aggressive acceleration, cold weather, tire pressure, and cargo or trailer weight can all shift your real-world result. Calculate MPG over several fill-ups and compare, rather than relying on a single tank, if you want a stable long-term average.

Frequently Asked Questions

How do I calculate MPG (miles per gallon)?
Divide the distance you drove by the gallons of fuel it took to drive that distance: MPG = Distance driven ÷ Fuel used. For example, driving 300 miles on 12 gallons gives 300 ÷ 12 = 25 MPG. The fill-up method — filling the tank, resetting your trip odometer, driving normally, then dividing the miles driven by the gallons needed to refill — is the most accurate way to measure fuel used.
How is cost per mile calculated?
Cost per mile equals the price per gallon divided by your miles per gallon: Cost per mile = Price per gallon ÷ MPG. This is mathematically the same as multiplying the gallons used by the price per gallon and dividing by the distance driven.
How much fuel will I need for a trip?
Divide the planned trip distance by your vehicle's MPG: Fuel needed = Trip distance ÷ MPG. Multiply that figure by the price per gallon to estimate the total fuel cost for the trip.
What counts as good fuel economy?
It depends heavily on vehicle type and driving conditions, so treat any figure as a general reference rather than a rule. Small and hybrid cars often exceed 35 to 40 MPG, midsize sedans commonly fall in the mid-20s to low-30s, and larger trucks and SUVs are often in the teens to low-20s. Highway driving, tire pressure, and cargo weight can shift your own result up or down.

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