Gas MPG Calculator
Gas mpg calculator works out Converted economy and Converted unit from Fuel economy, Entered in and Distance travelled. The default figures on this page give converted economy of 29.4018; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
2 steps
- 8 Litres per 100 kilometres (L/100km) = 12.5 km/L.
- 12.5 km/L = 29.401823 mpg-us.
Its 7 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
4 sources
What the gas mpg calculator calculates
Converts between miles per gallon (US and imperial), kilometres per litre and litres per 100 km, and works out trip fuel use, fuel cost and measured economy from distance and fuel volume.
How to use this gas mpg calculator
Enter Fuel economy, Entered in, Distance travelled and Distance unit. Converted economy updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Converted economy, Converted unit and Miles per US gallon.
The method follows NIST Handbook 44, Appendix C - General Tables of Units of Measurement, NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Weights and Measures ACT 1985 (UK), Schedule 1 and US EPA, Fuel Economy Guide - Fuel Economy and Annual Fuel Cost calculations.
What you can compare
Change one input at a time to see how it affects Converted economy, Converted unit and Miles per US gallon. The inputs you can vary are Fuel economy, Entered in, Distance travelled, Distance unit, Fuel used and Fuel volume unit.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
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Frequently asked questions
How do I calculate the MPG of my car?
Converts between miles per gallon (US and imperial), kilometres per litre and litres per 100 km, and works out trip fuel use, fuel cost and measured economy from distance and fuel volume. Open “How this is worked out” beside the result to see each step for your own figures.
Is 50 to 60 MPG good?
Converts between miles per gallon (US and imperial), kilometres per litre and litres per 100 km, and works out trip fuel use, fuel cost and measured economy from distance and fuel volume. On the figures this page opens with — fuel economy 1 — the converted economy is 29.4018. Put your own figures in their place and the working updates beside the result.
How do you calculate gas per gallon?
It needs Fuel economy, Entered in, Distance travelled, Distance unit, Fuel used and Fuel volume unit. Nothing else is required, and the figures stay in your browser.
How to calculate MPG without filling up?
The result gives Converted economy, Converted unit, Miles per US gallon, Miles per imperial gallon, Kilometres per litre and Litres per 100 km, each labelled with its unit so the figure can be read on its own.
What information do I need for the gas mpg calculator?
You need Fuel economy, Entered in, Distance travelled, Distance unit, Fuel used, Fuel volume unit and Fuel price. The page opens with default figures that give converted economy of 29.4018, so you can see the scale before entering your own.
What does this gas mpg calculator show?
It shows Converted economy, Converted unit, Miles per US gallon, Miles per imperial gallon, Kilometres per litre, Litres per 100 km, Miles per litre and Kilometres per US gallon, with the working and any warnings for your entries.