Gas Mileage Calculator
Fill up, divide, and see what you really get.
Your numbers
$
Your results
Miles per gallon (US)
Miles per gallon (US)
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Liters per 100 km
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Fuel cost per mile
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Cost of this fill-up
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Gas Mileage Calculator by TheCalcTools
How the Gas Mileage Calculator works
Fill the tank, note the odometer, drive, then fill again.
Enter the miles driven and the gallons you added to refill.
MPG is miles ÷ gallons; the tool also converts to L/100 km and cost per mile.
The formula
MPG = miles ÷ gallonsL/100 km = 235.215 ÷ MPG
Worked example
Using the default values shown in the calculator:
| Miles driven since last fill-up | 342 |
|---|---|
| Gallons added | 11.4 |
| Price per gallon | $3.6 |
- MPG = 342 ÷ 11.4 = 30.0.
- That is 7.84 L/100 km, costing $0.12 per mile; this fill-up cost $41.04.
Result:
| Miles per gallon (US) | 30.0 |
|---|---|
| Liters per 100 km | 7.84 |
| Fuel cost per mile | $0.12 |
| Cost of this fill-up | $41.04 |
Frequently asked questions
Why does my MPG differ from the dashboard?
Trip computers can overstate efficiency by a few percent. Hand calculations from fill-ups are more reliable.
How can I improve MPG?
Keep tires inflated, smooth acceleration, reduce speed on highways and remove unnecessary weight.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.