---
title: "Fuel Economy Calculator — Convert MPG, L/100km, km/L"
description: "Convert fuel economy between MPG (US), MPG (UK), L/100km, and km/L. Calculate real-world economy from trip distance and fuel used. Explains the US vs UK gallon difference."
url: "https://worldcalculators.org/calculators/fuel-economy/"
canonical: "https://worldcalculators.org/calculators/fuel-economy/"
---

# Fuel Economy Calculator

Convert fuel economy between MPG (US), MPG (UK), L/100km, and km/L. Calculate real-world economy from trip distance and fuel used. Explains the US vs UK gallon difference.

## Quick answer

30 MPG (US) = 7.84 L/100km = 12.75 km/L = 36.0 MPG (UK). The US and UK gallon are different sizes — use the converter below for exact figures.

## Frequently Asked Questions

Lower L/100km is always better — it is intuitive in the same way as cost per 100km. With MPG, a jump from 20 to 25 MPG saves twice as much fuel as a jump from 40 to 50 MPG, which is counterintuitive. Litres per 100km makes fuel savings directly proportional: going from 10 to 5 L/100km cuts fuel use in half.
Global averages vary significantly. US new car fleet average (CAFE standard) targets 49 MPG by 2026. EU WLTP average for new cars is around 5.5-6.5 L/100km. UK average is around 38-42 MPG (UK). Petrol cars worldwide average about 7-9 L/100km in real-world conditions.

Source: https://worldcalculators.org/calculators/fuel-economy/
Markdown mirror of the HTML page. Prefer this URL for RAG; the interactive calculator still lives on the HTML page.