Fuel Economy Converter

Convert between MPG (US & UK), km/L, and L/100km instantly. Supports both efficiency (higher = better) and consumption (lower = better) units.

Value
From
To
30 MPG (US) = — L/100km
Common Fuel Economy Conversions
MPG (US)MPG (UK)km/LL/100km
2024.028.5011.76
2530.0310.639.41
3036.0312.757.84
3542.0414.886.72
4048.0417.015.88
5060.0521.264.71

Frequently Asked Questions

US MPG uses the US gallon (3.785 L), while UK MPG uses the Imperial gallon (4.546 L). Since the Imperial gallon is about 20% larger, the same car gets ~20% more UK MPG than US MPG. A car rated at 30 US MPG is approximately 36 UK MPG. Always check which gallon a fuel economy rating uses.
L/100km is a consumption metric (lower = more efficient), while MPG and km/L are efficiency metrics (higher = more efficient). They have an inverse relationship: L/100km = 100 ÷ km/L. A car using 5 L/100km is more efficient than one using 8 L/100km.
To convert US MPG to L/100km: divide 235.215 by the MPG value. For UK MPG divide 282.481 by the value. For example, 30 US MPG = 235.215/30 ≈ 7.84 L/100km. To go the other way, divide those constants by the L/100km value to get MPG.
L/100km: EU countries, Canada, Australia, South Africa. km/L: Japan, India, Korea, parts of Asia. US MPG: United States. UK MPG: United Kingdom (though L/100km is also displayed). The EU mandates CO₂ g/km alongside fuel economy figures on new cars.
MPG measures distance per unit of fuel (higher = better), while L/100km measures fuel per unit of distance (lower = better). They have an inverse relationship: L/100km = 235.215 ÷ US MPG. This means improving from 20 to 25 MPG saves more fuel than going from 40 to 50 MPG, even though both are 5 MPG gains.
Key techniques to improve fuel economy: maintain proper tire pressure (saves 0.5–3%), reduce highway speed (fuel use rises with speed squared — driving 70 mph vs 60 mph uses ~17% more fuel), avoid rapid acceleration, remove roof racks when not in use, and keep the engine properly maintained. Air conditioning increases fuel use by up to 10–15%.
EPA fuel economy figures are measured on a chassis dynamometer in controlled lab conditions and are adjusted to reflect real-world driving. Still, real-world mpg typically runs 10–20% below the EPA estimate due to aggressive driving, cold weather, hills, load, and air conditioning. The EPA provides city, highway, and combined ratings; combined is typically closest to average driving.
MPGe (miles per gallon equivalent) compares electric vehicle efficiency to gasoline. The EPA defines 1 gallon of gasoline ≈ 33.7 kWh of energy, so MPGe = miles driven per 33.7 kWh used. A Tesla Model 3 rates about 132 MPGe combined. Higher MPGe means lower energy cost per mile driven.
Hybrids typically achieve 40–60 MPG (4–6 L/100km) in combined driving, compared to 25–35 MPG for comparable conventional cars. Full battery electric vehicles (BEVs) achieve the equivalent of 100–140 MPGe. PHEVs (plug-in hybrids) can run on electricity for short trips then switch to gasoline. EVs have no tailpipe emissions but their total environmental impact depends on how electricity is generated.
For MPG: Cost per mile = fuel price per gallon ÷ MPG. For example, $3.50/gal ÷ 30 MPG = $0.117/mile. For L/100km: Cost per km = (fuel price per liter × L/100km) ÷ 100. For example, $1.50/L × 7 L/100km ÷ 100 = $0.105/km. Multiply by distance to get trip fuel cost.

About This Fuel Economy Converter

This free fuel economy converter converts between miles per gallon (US mpg and UK mpg), litres per 100 km (L/100 km), and kilometres per litre (km/L). Enter a value in any unit for instant conversion.

When to use this converter

  • Comparing vehicle efficiency ratings between countries
  • Converting MPG to L/100 km for European driving or car shopping
  • Evaluating fuel cost over a planned road trip
  • Understanding rental car fuel economy abroad

Standards & References

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