Fuel Mileage Calculator

Enter your odometer readings (or trip distance), fuel used, and optional fuel price to calculate your vehicle's fuel mileage. Get results in MPG (US), MPG (Imperial), km/L, and L/100km — all four efficiency units at once — plus your total fuel cost for the trip.

mi / km

Record your odometer when you fill up the tank

mi / km

Record your odometer at the next fill-up

Total distance travelled on this tank of fuel

Amount of fuel added at the second fill-up

Enter fuel price to calculate total trip cost

Results

Fuel Economy (MPG US)

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MPG (Imperial)

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Kilometers per Liter

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Liters per 100 km

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Total Fuel Cost

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Cost per Mile (or km)

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Fuel Efficiency Across Units

Frequently Asked Questions

How do I calculate gas mileage (MPG)?

To calculate MPG, note your odometer reading when you fill up the tank. Drive normally, then fill up again and note the new odometer reading and the amount of fuel added. Subtract the first reading from the second to get miles driven, then divide that number by the gallons of fuel used. The formula is: MPG = Miles Driven ÷ Gallons Used.

What is the difference between MPG US and MPG Imperial?

A US gallon equals approximately 3.785 liters, while an Imperial (UK) gallon equals approximately 4.546 liters. This means Imperial MPG figures are always higher than US MPG for the same vehicle — roughly 20% higher. Always check which gallon standard is being used when comparing fuel economy figures.

How do I convert MPG to L/100km?

To convert US MPG to liters per 100 km, use the formula: L/100km = 235.21 ÷ MPG (US). For example, a car getting 30 MPG US achieves approximately 7.84 L/100km. Lower L/100km values indicate better fuel efficiency, while higher MPG values also indicate better efficiency.

How to improve gas mileage?

Key ways to improve fuel mileage include maintaining correct tire pressure, avoiding aggressive acceleration and hard braking, removing excess weight from the vehicle, keeping up with regular maintenance (clean air filters, fresh spark plugs), and reducing highway speeds. Driving at 55 mph instead of 75 mph can improve fuel economy by up to 20%.

What factors determine fuel efficiency?

Fuel efficiency is affected by vehicle type and size, engine displacement, drivetrain (FWD/RWD/AWD), tire condition and pressure, driving style, road conditions, weather, use of air conditioning, and vehicle load. Four-wheel drive systems generally consume more fuel than two-wheel drive because the engine must power additional components.

Should I use odometer readings or trip distance to calculate mileage?

Both methods give accurate results. Using odometer readings is convenient if you didn't reset your trip counter — just record the reading before and after a full tank. Using trip distance is easier if your vehicle has a trip odometer you reset at each fill-up. The key is to measure a full tank-to-tank cycle for the most accurate result.

How much does the average driver spend on fuel per year?

According to the American Automobile Association (AAA), the average American driver spends about $3,000 per year on gasoline. This varies significantly based on how many miles you drive, your vehicle's fuel efficiency, and local gas prices. Improving your MPG by even a few points can save hundreds of dollars annually.

What is a good MPG for a car?

For a gasoline-powered car, 30 MPG or above is considered good fuel economy. Compact and midsize sedans typically achieve 28–40 MPG combined, while SUVs and trucks range from 18–28 MPG. Hybrid vehicles can exceed 50 MPG combined. You can compare official EPA ratings at fueleconomy.gov to benchmark your vehicle's real-world performance.

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