MPG Calculator
Real fuel economy from your own fill-ups.
Enter your values
Enter the miles driven in miles.
Enter the gallons to refill in gal.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Fuel economy
- 30 mpg
- Litres per 100 km
- 7.84
- Kilometres per litre
- 12.75
- Imperial mpg
- 36.03
Working
- 1MPG = 342 ÷ 11.4 = 30
Quick answer
Fuel economy is miles driven divided by gallons used between two full fill-ups.
MPG = miles ÷ gallons
At a glance
| What it does | Real fuel economy from your own fill-ups. |
|---|---|
| Category | Auto |
| Inputs needed | Miles driven, Gallons to refill |
| Main output | Fuel economy |
| Formula | MPG = miles ÷ gallons |
| Cost | Free — no sign-up, no download |
How to use the MPG Calculator
- 1Fill the tank and reset the trip meter.
- 2At the next fill-up, note the miles and gallons.
- 3Enter both to get true economy.
Inputs explained
- Miles driven(miles)
- Enter the miles driven in miles.
- Gallons to refill(gal)
- Enter the gallons to refill in gal.
Worked example
Using the values the calculator loads with:
Inputs
- Miles driven342 miles
- Gallons to refill11.4 gal
Results
- Fuel economy30 mpg
- Litres per 100 km7.84
- Kilometres per litre12.75
- Imperial mpg36.03
- MPG = 342 ÷ 11.4 = 30
Frequently asked questions
Why is my mpg worse in winter?
Cold engines run rich, winter fuel blends carry less energy, and heaters and denser air all reduce economy by 10–20%.
What is UK mpg?
Imperial mpg, based on the larger imperial gallon, so it reads about 20% higher than the US figure for the same car.
What do I need to enter into the MPG Calculator?
Just 2 values: miles driven, gallons to refill. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the MPG Calculator work out the answer?
Fuel economy is miles driven divided by gallons used between two full fill-ups. It applies the formula MPG = miles ÷ gallons and shows the working so you can check each step by hand.
Is the MPG Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.