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Convert Kilometers per Liter to Liters per 100 Kilometers - Fuel Economy Converter

This converter transforms fuel economy expressed in kilometres per litre (km/L) into litres consumed per 100 kilometres (L/100 km), a common metric used in regulatory reporting and vehicle comparison in many countries.

The conversion is a fixed mathematical inversion widely used by engineering teams and government agencies to compare vehicle fuel consumption on a uniform scale.

Updated Nov 20, 2025

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Methodology

The conversion uses a direct reciprocal relationship between the two units: one measures distance traveled per unit of fuel (km/L) and the other measures fuel used per fixed distance (L/100 km). Multiply the reciprocal of km/L by 100 to express fuel use per 100 kilometres.

This approach aligns with measurement conventions used by national laboratories and transport agencies. For presentation we recommend reporting results to two or three decimal places depending on the precision of the input data and the instrument accuracy.

Worked examples

Example 1: 15.0 km/L → L/100 km = 100 ÷ 15.0 = 6.666... → report 6.667 L/100 km (3 dp).

Example 2: 8.5 km/L → L/100 km = 100 ÷ 8.5 = 11.7647 → report 11.765 L/100 km (3 dp).

Example 3: 0.0 km/L is undefined — the conversion requires a positive km/L value (vehicle not moving or infinite consumption cannot be converted).

Key takeaways

Conversion is exact and reversible (L/100 km = 100 ÷ (km/L); km/L = 100 ÷ (L/100 km)).

Use this converter for quick unit translations when comparing fuel economy figures from different sources or regulations.

Further resources

Expert Q&A

What is the exact mathematical relationship between km/L and L/100 km?

They are reciprocal measurements scaled to 100 km. L/100 km = 100 ÷ (km per L). Conversely, km/L = 100 ÷ (L per 100 km).

How many decimal places should I report?

For consumer-facing displays, 2–3 decimal places are typical. For regulatory or engineering work, follow the precision rules in the applicable test procedure or dataset. If your input comes from an onboard trip computer, match the device's reported precision.

Can I convert zero or negative values?

No. The conversion requires a positive km/L value. Zero or negative inputs are physically invalid for fuel economy and will not produce a meaningful L/100 km result.

Why might my vehicle's onboard computer and this calculator give slightly different results?

Differences arise from measurement windows, sensor calibration, rounding, and whether the onboard system uses estimated fuel flow versus tank-burn measurements. Regulatory test cycles and lab measurements use controlled procedures that differ from real-world onboard averaging.

How does this conversion relate to regulatory reporting?

Transport and environment agencies publish fuel consumption and greenhouse gas metrics in L/100 km for broad comparability. Use the converted number as a unit-aligned value but follow the specific test or reporting protocol when submitting regulatory data.

How do I convert from imperial MPG to L/100 km?

First convert MPG (US or UK) to km/L using the appropriate factor for the MPG variant, then apply L/100 km = 100 ÷ (km/L). Use authoritative conversion factors from national metrology institutes or government fuel-economy publications for precise work.

Does temperature, altitude, or fuel quality affect the conversion?

The mathematical conversion is unaffected by conditions. However, those factors influence actual fuel consumption measurements; account for them when interpreting real-world fuel-economy figures.

Is this converter suitable for high-precision engineering analyses?

The conversion is exact, but the accuracy of the result depends on the input's measurement quality. For engineering or certification work, use instrument-calibrated data and follow the precision and uncertainty requirements from standards bodies.

Sources & citations