# Fuel Economy Converter

Free fuel economy converter. Convert between MPG (US & imperial), liters per 100 km, and kilometers per liter with exact conversion factors.

## What this calculates

Convert between all major fuel economy units: miles per gallon (US and imperial), liters per 100 kilometers, and kilometers per liter. Uses exact gallon and mile definitions.

## Inputs

- **Value** — min 0
- **From** — options: Miles per US gallon (MPG), Miles per imperial gallon, Liters per 100 km (L/100km), Kilometers per liter (km/L)
- **To** — options: Miles per US gallon (MPG), Miles per imperial gallon, Liters per 100 km (L/100km), Kilometers per liter (km/L)

## Outputs

- **Result** — The converted fuel economy value.
- **Conversion** — formatted as text — Step-by-step conversion explanation.

## Details

Fuel economy is expressed differently around the world. The US uses miles per gallon (MPG), most of Europe and many other countries use liters per 100 km (L/100km), and some countries use km/L.

Key Differences

- MPG and km/L: Higher number = better fuel economy

- L/100km: Lower number = better fuel economy (inverse relationship)

- US gallon ≠ imperial gallon (US: 3.785 L, Imperial: 4.546 L)

Conversion Factors

- 1 US MPG = 0.4251 km/L

- 1 imperial MPG = 0.3540 km/L

- 30 US MPG ≈ 7.84 L/100km

- 1 US gallon = 3.785411784 liters (exact)

- 1 imperial gallon = 4.54609 liters (exact)

- 1 mile = 1.609344 km (exact)

## Frequently Asked Questions

**Q: How do I convert MPG to L/100km?**

A: Divide 235.215 by the MPG value (US gallons). For example, 30 MPG = 235.215 / 30 = 7.84 L/100km. Note that MPG and L/100km have an inverse relationship: higher MPG means lower L/100km.

**Q: What is the difference between US and imperial gallons?**

A: A US gallon is 3.785411784 liters while an imperial gallon is 4.54609 liters (about 20% larger). This means the same car will have a higher MPG number when measured in imperial gallons. Always check which gallon standard is being used.

**Q: What is good fuel economy?**

A: Good fuel economy depends on vehicle type. For passenger cars: 30-40 MPG (US) or 5.9-7.8 L/100km is considered good. Hybrid vehicles achieve 40-60 MPG. SUVs and trucks typically get 20-30 MPG. Electric vehicles are often rated in MPGe (miles per gallon equivalent).

**Q: Why does Europe use L/100km instead of MPG?**

A: L/100km directly tells you how much fuel you will use for a given distance, making it easy to calculate trip costs. It also has a more linear relationship with fuel consumption changes. A drop from 10 to 8 L/100km always saves 2L per 100km, regardless of starting point.

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Source: https://vastcalc.com/calculators/everyday/fuel-economy-converter
Category: Everyday Life
Last updated: 2026-04-21