⛽ MPG Calculator
Enter the miles you drove and the gallons you used to find your real fuel economy — in miles per gallon and the metric equivalents, litres per 100 km and kilometres per litre.
🚗 Miles & Gallons
What is an MPG Calculator?
It turns a simple tank-to-tank measurement — miles driven and gallons burned — into your true fuel economy, then shows the same result in metric so a US figure and a European one line up. Tracking real MPG catches problems early: a sudden drop can flag low tire pressure, a dragging brake, a dirty air filter, or a failing sensor.
Use it after each fill-up to benchmark your car, compare driving styles, or estimate fuel for a trip. The numbers are estimates for planning — economy swings with conditions, so average a few tanks for the clearest picture.
❓ Frequently Asked Questions
How do I calculate my car's MPG?
Fill the tank, reset the trip meter, drive, then refill. Divide the miles you covered by the gallons it took to top up: MPG = miles ÷ gallons. That tank-to-tank method gives your real-world economy, which is usually more useful than the dashboard estimate or the EPA window-sticker figure.
How does MPG convert to litres per 100 km?
The two scales are inverses — MPG measures distance per fuel, while L/100 km measures fuel per distance — so you can't just multiply by a single factor. The calculator uses the standard conversion 235.215 ÷ MPG to give litres per 100 km, and also shows kilometres per litre, so the same drive is readable in both US and metric terms.
Why is my real MPG lower than the sticker rating?
Lab and EPA figures run a standardized cycle that rarely matches your commute. City traffic, short trips before the engine warms, hard acceleration, high speeds, cold weather, roof racks, low tire pressure, and extra cargo all cut economy. Measuring a few tanks yourself shows what the car actually returns in your conditions.
Are the results exact?
The math is exact, but the inputs depend on how completely you fill the tank and how accurately you log miles. These are estimates for planning; real-world economy varies by driving style, terrain, load, weather, and vehicle condition. Average several tanks for a more reliable figure.