How to Convert MPG to L/100km (and Back)
Miles per gallon (MPG) and liters per 100 kilometers (L/100km) both measure fuel economy, but they work in opposite directions — a higher MPG means better efficiency, while a lower L/100km means better efficiency. This makes direct comparison tricky. This guide explains both units, gives the exact conversion formula, and provides a practical reference table.
What Is MPG?
Miles per gallon (MPG) measures how many miles a vehicle travels on one gallon of fuel. A higher number means better fuel economy. It is the standard fuel efficiency unit in the United States.
US EPA fuel economy ratings use MPG. A fuel-efficient compact car might achieve 35–45 MPG combined. A typical SUV gets 20–28 MPG. Hybrid vehicles can reach 50+ MPG.
Note: US MPG uses the US gallon (3.785 L). UK MPG uses the imperial gallon (4.546 L) — so UK MPG figures are about 20% higher than US MPG for the same vehicle.
What Is L/100km?
Liters per 100 kilometers (L/100km) measures how many liters of fuel a vehicle consumes per 100 km traveled. A lower number means better fuel economy — the opposite logic from MPG.
L/100km is the standard fuel efficiency unit in Europe, Australia, Canada, and most of the world. A fuel-efficient car achieves 5–7 L/100km. An SUV might use 9–12 L/100km.
The Conversion Formula
MPG and L/100km are inversely related. The conversion constant is 235.215 (derived from liters per US gallon × km per mile).
MPG to L/100km: divide 235.215 by the MPG value. Example: 30 MPG = 235.215 ÷ 30 = 7.84 L/100km.
L/100km to MPG: divide 235.215 by the L/100km value. Example: 8 L/100km = 235.215 ÷ 8 = 29.4 MPG.
MPG to L/100km Reference Table
Common values for US MPG:
- 20 MPG = 11.76 L/100km (typical truck/large SUV)
- 25 MPG = 9.41 L/100km (typical mid-size SUV)
- 30 MPG = 7.84 L/100km (typical sedan)
- 35 MPG = 6.72 L/100km (efficient compact)
- 40 MPG = 5.88 L/100km (hybrid)
- 50 MPG = 4.70 L/100km (efficient hybrid)
- 60 MPG = 3.92 L/100km (top hybrid efficiency)
US MPG vs UK MPG
Because the UK imperial gallon (4.546 L) is larger than the US gallon (3.785 L), a UK MPG figure is about 20% higher than US MPG for the same vehicle.
To convert UK MPG to L/100km, use 282.48 instead of 235.215 as the conversion constant. For most comparisons, stick to L/100km as the common language between US and European efficiency ratings.
Conclusion
MPG and L/100km are inversely related — use 235.215 as the conversion constant for US gallons. To convert: divide 235.215 by the MPG value to get L/100km, or divide 235.215 by L/100km to get MPG. Use our free fuel economy converter for instant results.