Calculating your litres per 100 km (l/100km) is straightforward once you know the Fuel Economy Converter formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Fuel Economy Converter.
What is Fuel Economy Converter?
The Fuel Economy Converter calculation tells you your litres per 100 km (l/100km) from a few simple inputs. The figure you are solving for here is the litres per 100 km (l/100km).
The Fuel Economy Converter formula
This calculation combines several inputs through a multi-step method rather than a single one-line formula. Enter the values below and the calculator resolves each step in order. The inputs it needs are:
- Fuel economy value — a number. Example: 15.
- From unit — one of: Kilometres per litre (km/L), Miles per gallon, US (mpg), Litres per 100 km (L/100km). Example: Kilometres per litre (km/L).
How to calculate it step by step
- Write down the fuel economy value (for example, 15).
- Choose the from unit (for example, Kilometres per litre (km/L)).
- Apply the formula above to get your litres per 100 km (l/100km).
- Double-check the result with the Fuel Economy Converter.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Fuel economy value | 15 |
| From unit | Kilometres per litre (km/L) |
| Litres per 100 km (L/100km) | 6.667 |
| Kilometres per litre (km/L) | 15.000 |
| Miles per gallon, US (mpg) | 35.282 |
With fuel economy value of 15 and from unit of Kilometres per litre (km/L), the litres per 100 km (l/100km) works out to 6.667.
Example 2
With fuel economy value of 30 and from unit of Kilometres per litre (km/L), the litres per 100 km (l/100km) works out to 3.333.
| Result | Value |
|---|---|
| Litres per 100 km (L/100km) | 3.333 |
| Kilometres per litre (km/L) | 30.000 |
| Miles per gallon, US (mpg) | 70.564 |
Example 3
With fuel economy value of 7.5 and from unit of Kilometres per litre (km/L), the litres per 100 km (l/100km) works out to 13.333.
| Result | Value |
|---|---|
| Litres per 100 km (L/100km) | 13.333 |
| Kilometres per litre (km/L) | 7.500 |
| Miles per gallon, US (mpg) | 17.641 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Fuel Economy Converter does it instantly, for free, with the formula and a worked example built in.
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