Is my data uploaded to a server?

No. All calculations run locally in your browser using JavaScript.

Why are US MPG and UK MPG different?

The US gallon (3.785 L) and the UK imperial gallon (4.546 L) are different volumes. A car rated at 30 MPG US only achieves about 25 MPG UK, even though the car has not changed. Always check which MPG standard a specification uses.

My car shows L/100km — how do I convert to MPG?

Use the formula: MPG (US) = 235.215 / L100km. For example, 8 L/100km = 235.215/8 = 29.4 MPG US. This tool does the calculation automatically.

What is the most fuel-efficient unit to use?

L/100km is considered the most intuitive for comparing fuel costs — a lower number directly means less fuel used per distance. MPG is inverse (higher is better), which can be misleading when comparing improvements.

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Fuel Efficiency Converter

Convert between MPG (US & UK), L/100km, km/L and other fuel economy units instantly. Free, browser-based, no signup.

🔄 Conversion Tools Free Browser-based

Tool

Value

Unit

Trip cost calculator

Distance (km)

Fuel price (per litre)

Estimated cost

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Fuel Efficiency Units

Different countries use different conventions. The US and UK use miles per gallon (MPG), but US and UK gallons differ — 1 US gallon = 3.785 litres, 1 UK imperial gallon = 4.546 litres. Most of Europe and Asia use litres per 100 kilometres (L/100km). Higher MPG and km/L values mean better efficiency; lower L/100km means better efficiency.

Typical Vehicle Efficiency

Vehicle Type	MPG (US)	L/100km	km/L
Large SUV / truck	15–20	12–16	6–8
Family sedan	28–35	7–8.5	12–14
Economy car	35–45	5.5–7	14–18
Hybrid	45–55	4–5.5	18–22
EV (MPGe)	100–140	—	—

Conversion Formula

L/100km ↔ MPG (US): MPG = 235.215 / L100km. Note this is an inverse relationship — doubling the MPG halves the L/100km value.

Fuel Efficiency Converter

Fuel Efficiency Units

Typical Vehicle Efficiency

Conversion Formula

Frequently Asked Questions