Convert a reported fuel value
- Enter a positive consumption or economy value and choose its unit, or choose distance and fuel used over the same period.
- Choose the target unit, checking whether MPG uses a US or Imperial gallon.
- Convert, review both consumption and economy, then copy or download.
Reciprocal formulas and gallon definitions
8 L/100 km = 12.5 km/L ≈ 29.401823 mpg (US) or 35.310117 mpg (Imperial). Lower L/100 km means less fuel per fixed distance; higher km/L or MPG means more distance per fixed fuel amount.
| Input unit | Formula |
|---|---|
| L/100 km | C = x |
| km/L | C = 100 / x |
| US MPG | C = (100 × 3.785411784 / 1.609344) / x |
| Imperial MPG | C = (100 × 4.54609 / 1.609344) / x |
One mile is 1.609344 km. A US liquid gallon is 3.785411784 L, an Imperial gallon 4.54609 L. Reverse each formula to obtain the target value. Full constants are used without rounding to 235.215 or 282.481 during calculation. See NIST’s fuel-consumption table and the definitions in the volume converter.
Limits and privacy
Finite source values greater than zero and up to 10¹⁵. Zero, negative and arithmetic overflow/underflow cases are rejected; the tool does not substitute an infinite economy value. Trip entry calculates consumption = 100 × litres used ÷ kilometres travelled. Both quantities must be positive and at most 10¹⁵; the resulting consumption must be representable and at most 10¹⁵ L/100 km. This converts supplied measurements without predicting a vehicle’s actual consumption, emissions, range or fuel cost. Electric energy-per-distance units, combined fuel economies and trip aggregation are not supported.
Display uses up to 12 significant digits and six decimal places or scientific notation, CSV retains the finite floating-point result. Inputs stay in browser memory with no requests, uploads or saved values. Live conversion waits 300 ms and immediately clears obsolete results on edits. The comparison table and CSV cover all four measures; selected CSV retains original trip quantities and units when used. Swap preserves the number while exchanging units; result reuse preserves the raw fuel figure and returns trip entry to a reported figure. Those actions, examples and Reset support one Undo step; edits clear that history. Reset clears output and restores 8 L/100 km to US MPG.
Can I average MPG values directly?
This converter does not aggregate trips. For an overall measured economy, use total distance divided by total fuel; an arithmetic mean of individual MPG values can misrepresent that total.