Fuel Economy Converter

⛽

US MPG • L/100km • km/L • UK MPG

Fuel Economy Value ⓘ

From

⛽

Enter fuel economy to convert

How to Use the Fuel Economy Converter

Enter fuel economy value — e.g., 30 for 30 MPG or 7.5 for 7.5 L/100km.
Select From unit — US MPG (American standard), L/100km (European), km/L (Asian/metric), or UK MPG (British Imperial).
Select To unit — your target unit.
Results panel — shows all four fuel economy metrics simultaneously plus an efficiency gauge.
Note — L/100km is an inverse scale: lower = more efficient. MPG and km/L are direct: higher = more efficient.

Benefits

🚗

Compare Car Specs

Easily compare US EPA ratings (MPG) with European fuel economy (L/100km) when researching imported vehicles.

🌍

International Travel

Understand rental car fuel specs and gas station pricing per liter in any country.

💰

Fuel Cost Planning

Know exactly how much fuel your trip will cost in any country's measurement system.

Fuel Economy Conversion Guide — MPG, L/100km, km/L

Fuel economy conversion is increasingly important as Americans buy European or Asian cars, travel abroad, or compare vehicles across international markets. The US uses miles per gallon (MPG) while Europe uses liters per 100 kilometers (L/100km) and many Asian markets use kilometers per liter (km/L). These are not simple multiplication conversions — converting MPG to L/100km requires using 235.214 as the conversion constant.

Key formulas: L/100km = 235.214 ÷ US MPG. US MPG = 235.214 ÷ L/100km. km/L = US MPG × 0.425144. UK MPG = US MPG × 1.20095 (UK gallon is 20% larger). A "30 MPG" US car = 7.84 L/100km. A European "5 L/100km" car = 47.1 US MPG. 40 MPG US = 5.88 L/100km = 17.01 km/L.

📊

US MPG Reference

Poor: under 20 mpg. Average: 25–35 mpg. Good: 35–50 mpg. Hybrid: 45–60 mpg. EV equivalent: 80–130 MPGe. 2024 CAFE standard: 49 mpg fleet average.

🇪🇺

European L/100km

Poor: above 10 L/100km. Average: 6–8 L/100km. Good: 4–6 L/100km. Excellent: under 4 L/100km. EU 2030 target: 1.4 L/100km CO₂ equivalent average.

🛢️

Fuel Cost Example

At $3.50/gal & 30 MPG: 100 miles costs $11.67. At €1.80/L & 7 L/100km: 100 km costs €12.60. Cost per mile: MPG-car = price÷mpg. Cost per km: L/100km-car = (price×L100km)÷100.

🔋

EV: MPGe

Miles Per Gallon equivalent: 33.7 kWh = 1 gallon energy. Tesla Model 3: 132 MPGe. Nissan Leaf: 111 MPGe. Chevy Bolt: 120 MPGe. EV cost equivalent: 33.7 kWh at $0.14 = $4.72 vs $3.50 gas at 30 MPG for same miles.

Formula & Logic

Fuel economy is the rare conversion where the two systems are not merely scaled but inverted. Miles per gallon measures distance per unit fuel, so higher is better, while litres per 100 kilometres measures fuel per unit distance, so lower is better. Converting requires a reciprocal, which has a consequence people find counter-intuitive: equal MPG improvements do not represent equal fuel savings. Going from 15 to 20 MPG saves far more fuel over the same distance than going from 40 to 45, which is precisely why regulators prefer the litres-per-100 km form.

L/100km = 235.215 ÷ US MPGUS MPG = 235.215 ÷ L/100kmImperial MPG = US MPG × 1.201km/L = L/100km ÷ 100, inverted

where:

235.215: derived from 100 × 3.785411784 ÷ 1.609344 — the US gallon and mile definitions
US MPG: US gallons; the imperial gallon is 20% larger so imperial MPG reads higher
L/100km: the EU standard — lower is better

Assumptions: Ratings depend on the test cycle as much as the unit: EPA, WLTP and NEDC figures for the same vehicle differ substantially, and none predicts individual real-world consumption.

SourceEPA fuel economy label

Step-by-Step Example: 32 US MPG in Metric, and Why the Inverse Matters

Convert a US window-sticker figure, then test the non-linearity.

Rated economy32 US MPG

Apply the constant: 235.215 ÷ 32 = 7.35 L/100km.
To imperial MPG: 32 × 1.201 = 38.4 imperial MPG — the same car, a bigger number.
Now the non-linearity. Fuel to drive 100 km at 32 MPG: 7.35 L.
Improve to 37 MPG: 235.215 ÷ 37 = 6.36 L/100km, saving 0.99 L per 100 km.
Now improve a thirsty car from 15 to 20 MPG: 15.68 → 11.76 L/100km, saving 3.92 L per 100 km.
The same 5 MPG gain saves four times as much fuel at the thirsty end.

Result32 US MPG = 7.35 L/100km = 38.4 imperial MPG

This is the "MPG illusion": replacing one 15 MPG vehicle with a 20 MPG one saves more fuel than replacing four 40 MPG cars with 45 MPG ones. Ranking upgrades by MPG gained gets the priority backwards.

Fuel Economy FAQ

How do you convert MPG to L/100km? ▾

L/100km = 235.214 ÷ MPG (US). This formula works because 1 US gallon = 3.78541 L and 1 mile = 1.60934 km. Example: 30 MPG = 235.214 ÷ 30 = 7.84 L/100km. 25 MPG = 9.41 L/100km. 40 MPG = 5.88 L/100km. 50 MPG = 4.70 L/100km. Note: use 282.481 ÷ UK MPG for L/100km when working with Imperial gallons.

Why is US MPG different from UK MPG? ▾

The US gallon = 3.78541 liters while the UK (Imperial) gallon = 4.54609 liters — a 20% difference. A car rated at 40 UK MPG = 33.3 US MPG. This confusion arose because both countries use "miles" but different gallon sizes. When comparing UK and US car fuel economy claims, always check which gallon is used. European specs use L/100km, eliminating the ambiguity entirely.

What is a good fuel economy in MPG? ▾

For a non-hybrid gas car in 2024–2026: Under 20 MPG = poor (large trucks/SUVs). 20–30 MPG = below average. 30–40 MPG = good. 40–50 MPG = excellent. 50+ MPG = top tier (typically hybrids). Plug-in hybrids can achieve 50–60 MPG. Full EVs are rated in MPGe: 80–130 MPGe is typical. The EPA CAFE standard requires automakers to average ~49 MPG fleet-wide by 2026.

How do I calculate fuel cost from MPG? ▾

Fuel cost = (distance ÷ MPG) × price per gallon. Example: 300 miles ÷ 30 MPG = 10 gallons × $3.50 = $35 total cost. Cost per mile = price per gallon ÷ MPG. At $3.50 and 30 MPG: $3.50 ÷ 30 = $0.117 per mile. For L/100km: cost = (distance in km ÷ 100) × L/100km rating × price per liter. At €1.80/L and 7 L/100km: 100 km costs 7 × €1.80 = €12.60.

Related Converters