What is the exact conversion factor from UK MPG to km/L?

1 UK MPG = 0.354006 km/L. This comes from 1 mile = 1.609344 km and 1 Imperial gallon = 4.54609 L, giving 1.609344 / 4.54609 ≈ 0.354006.

How is UK MPG different from US MPG?

The UK uses the Imperial gallon (4.54609 L) while the US uses the US liquid gallon (3.78541 L). The same vehicle will show a higher MPG figure on the UK scale. 1 UK MPG ≈ 0.354006 km/L, while 1 US MPG ≈ 0.425144 km/L.

How do I convert km/L back to UK MPG?

Divide the km/L value by 0.354006. For example, 15 km/L ÷ 0.354006 ≈ 42.4 MPG (UK). You can also use the Swap button in this tool to flip the direction.

What is a good fuel economy in km/L for a UK car?

A typical efficient UK car gets around 15–20 km/L (roughly 42–57 MPG UK). Hybrids and small diesels often exceed 20 km/L. Larger SUVs and older engines usually fall below 12 km/L.

Why does the UK MPG look higher than the US MPG for the same car?

Because the Imperial gallon is about 20% larger than the US gallon. A car that travels further per Imperial gallon will show a proportionally higher MPG number compared to the US rating for the same car.

Can I convert UK MPG to L/100km?

Yes. First convert to km/L using this tool, then calculate 100 ÷ km/L to get L/100km. For example, 50 MPG UK ≈ 17.7 km/L → 100 ÷ 17.7 ≈ 5.65 L/100km.

MPG (UK) to km/L Converter

Enter a fuel economy value in UK (Imperial) MPG and instantly get the equivalent in km/L (1 MPG UK = 0.354006 km/L).

Fuel Economy Converter

Miles Per Gallon (UK / Imperial MPG)

MPG UK

Kilometers Per Liter (km/L)

km/L

Result

Enter a value to see the result

1 UK MPG = 0.354006 km/L | 1 km/L ≈ 2.82481 MPG (UK)

Common Conversions

MPG (UK)	km/L	Typical Vehicle

Summary

This converter turns any UK (Imperial) MPG value into km/L in real time using the exact factor: 1 MPG UK = 0.354006 km/L, derived from 1 Imperial gallon = 4.54609 L and 1 mile = 1.609344 km. All math runs in your browser — no server call needed. You can also reverse the conversion and copy the result with one click. A reference table shows common vehicle classes in both units for quick comparison.

How it works

Enter your fuel economy value in the UK MPG or km/L field.
The converter applies the exact factor: 1 MPG (UK) = 0.354006 km/L.
The equivalent value appears instantly in the other field.
Use the Swap button to reverse the conversion direction.
Copy the result with one click for use elsewhere.

Use cases

Convert a British or Australian car spec sheet from MPG to km/L.
Compare fuel economy figures when buying an imported UK-spec vehicle.
Understand fuel efficiency ratings on European and Asia-Pacific markets.
Cross-check rental car economy for trips between the UK and metric countries.
Validate fuel cost estimates when switching between UK and metric fuel records.
Convert classic British vehicle MPG figures into modern metric equivalents.

Frequently Asked Questions

Last updated: 2026-09-09 · Reviewed by Nham Vu