Everyday
Fuel Economy Calculator
Use this fuel economy calculator to compare vehicle efficiency and estimate trip fuel costs.
Try an example
Result
Fuel economy
—
- Trip fuel cost
- —
- Miles per gallon
- —
- L/100 km
- —
Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the fuel economy calculator solves
Use this fuel economy calculator to compare vehicle efficiency and estimate trip fuel costs.
Formula
How to use it
- Choose miles/gallons or kilometers/liters.
- Enter distance and fuel used.
- Add fuel price to estimate trip cost.
How to read the answer
Higher MPG is better. Lower L/100 km is better.
Common mistakes and edge cases
- Do not compare MPG and L/100 km as if both higher is better.
- Use actual fuel used for best accuracy.
- Fuel price should match the fuel unit you selected.
Worked examples
Road trip MPG
Fuel economy
30 mpg / 7.84 L/100 km
Metric efficiency
Fuel economy
33.6 mpg / 7 L/100 km
Frequently asked questions
Is higher MPG always better?+
For fuel economy, yes. For L/100 km, lower is better.
Can this estimate trip cost?+
Yes. Enter fuel price per gallon or liter to match your input mode.
About this calculator
- Written by
- mathcheck editorial team
- Last reviewed
- May 8, 2026
Method
- Uses the values entered by the user and stable formulas documented on the page.
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Last updated: May 8, 2026