MPG to L/100km Converter Formula

Understand the math behind the mpg to l/100km converter. Each variable explained with a worked example.

Use the MPG to L/100km Converter

Formulas Used

Liters per 100 km

lper100km = 235.215 / mpg

Kilometers per Liter

kmperliter = mpg * 0.425144

Variables

VariableDescriptionDefault
mpgFuel Economy (MPG)(mpg)30

How It Works

How to Convert MPG to L/100km

Formula

L/100km = 235.215 / MPG

This conversion uses the relationship: 1 US gallon = 3.78541 liters and 1 mile = 1.60934 km. The constant 235.215 comes from (100 * 3.78541) / 1.60934. Note that MPG and L/100km have an inverse relationship: higher MPG means lower L/100km.

Key Difference

MPG measures distance per fuel unit (higher is better). L/100km measures fuel per distance unit (lower is better). This inverse relationship means the conversion is a division, not a multiplication.

Worked Example

Convert 30 MPG (US) to L/100km.

mpg = 30
  1. 01Apply the reciprocal formula: L/100km = 235.215 / MPG
  2. 02L/100km = 235.215 / 30 = 7.84 L/100km
  3. 03Also: km/L = 30 * 0.425144 = 12.75 km/L

Frequently Asked Questions

Why is the conversion a division and not a multiplication?

MPG measures distance per fuel unit while L/100km measures fuel per distance unit. These are reciprocal measures, so the conversion involves dividing a constant by the MPG value rather than multiplying.

Is US MPG the same as UK MPG?

No. The US gallon (3.785 L) is smaller than the Imperial gallon (4.546 L). A car rated at 30 US MPG would be rated at approximately 36 Imperial MPG. This converter uses US gallons.

What is a good L/100km value?

For a typical passenger car, under 6 L/100km is excellent, 6-8 is good, 8-10 is average, and over 10 is below average. Hybrids can achieve 4-5 L/100km and EVs effectively achieve 0.

Ready to run the numbers?

Open MPG to L/100km Converter