Gas Mileage Calculator – MPG, Cost per Mile & L/100km
Miles per Gallon (MPG)
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Cost per Mile
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L/100km
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Distance Driven
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Total Fuel Cost
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How to Track and Improve Your Fuel Economy
Knowing your actual gas mileage helps you budget for fuel costs and identify changes in your vehicle's efficiency. To get accurate results, fill your tank completely, note your odometer reading, drive as you normally would, then fill up again and record how many gallons it took. Divide the miles driven by the gallons used to get your MPG. This calculator does that math instantly and also converts your result to liters per 100 kilometers for international comparison.
Cost per mile is calculated by dividing the fuel cost by the distance driven. This metric is valuable for budgeting road trips, calculating commute costs, and comparing the running costs of different vehicles. For example, at $3.50 per gallon and 28 MPG, your cost per mile is about $0.125. Over a 15,000-mile year, that totals approximately $1,875 in fuel alone.
The fill-up tracking feature lets you log multiple fill-ups to see your average fuel economy over time. This is more accurate than a single measurement because driving conditions vary. You may notice your MPG drops in winter due to cold starts and denser fuel blends, or improves on highway road trips. Keeping a log also helps you spot potential issues — a sudden drop in MPG could indicate underinflated tires, a dirty air filter, or a mechanical problem that needs attention.
Frequently Asked Questions
How do I calculate gas mileage (MPG)?
Divide the miles driven by the gallons used. For example, 300 miles / 10 gallons = 30 MPG. Fill your tank, note the odometer, drive normally, fill up again, and note the gallons — that gives you the most accurate reading.
How do I convert MPG to L/100km?
Divide 235.215 by your MPG value. For example, 30 MPG = 235.215 / 30 = 7.84 L/100km. The relationship is inverse: higher MPG means lower L/100km.
What is a good gas mileage for a car?
Sedans: 30-40 MPG. SUVs: 25-30 MPG. Trucks: 20-25 MPG. Hybrids: 40-60 MPG. The EPA average for all new vehicles is about 26 MPG.
Why does my actual MPG differ from the EPA estimate?
Real-world MPG varies due to driving conditions, habits, and maintenance. City driving, aggressive acceleration, high speeds, cold weather, AC use, and underinflated tires all reduce MPG.