Why is UK MPG higher than US MPG for the same car?

The UK (imperial) gallon is larger than the US gallon — 4.54609 L vs 3.785411784 L. So a car traveling the same distance uses fewer UK gallons, giving a higher MPG figure. A car rated 50 MPG (UK) is equivalent to about 41.6 MPG (US) for the same real-world efficiency.

What is the exact conversion factor from UK MPG to US MPG?

Multiply UK MPG by 0.832674 (= 3.785411784 / 4.54609). For example, 50 MPG (UK) × 0.832674 = 41.63 MPG (US).

How do I convert US MPG to UK MPG?

Divide US MPG by 0.832674 (or multiply by 1.20095). For example, 30 MPG (US) ÷ 0.832674 = 36.03 MPG (UK).

Is US MPG the same as Canadian MPG?

Yes — Canada uses US gallons for MPG figures in informal use, though official Canadian ratings are published in L/100 km. This converter handles UK (imperial) vs US gallons only.

How does MPG relate to L/100 km?

To convert UK MPG to L/100 km, divide 282.481 by the UK MPG value. To convert US MPG to L/100 km, divide 235.215 by the US MPG value.

MPG (UK) to MPG (US) Converter

Name: MPG (UK) to MPG (US) Converter
Availability: InStock
Author: Nham Vu

Enter UK (imperial) MPG to get the US MPG equivalent instantly, with a reverse converter and reference table included.

Converter

UK MPG (miles per imperial gallon)

= — MPG (US)

US MPG (miles per US gallon) — reverse

= — MPG (UK)

1 MPG (UK) = 0.832674 MPG (US) | Factor = 3.785411784 ÷ 4.54609

Common conversions

MPG (UK)	MPG (US)

The UK imperial gallon (4.54609 L) is about 20% larger than the US gallon (3.785 L), so UK MPG figures are always higher than US MPG for the same vehicle.

Summary

Enter UK (imperial) MPG to get the US MPG equivalent instantly, with a reverse converter and reference table included.

How it works

Enter a fuel economy value in UK MPG in the top input field.
The US MPG result appears instantly — no button needed.
Use the reverse field to convert US MPG back to UK MPG.
Click "Copy" next to any result to copy it to your clipboard.
Click any row in the reference table to populate the converter.

Use cases

Compare fuel economy specs between British and American car listings.
Convert UK manufacturer MPG ratings to US MPG for American buyers.
Verify vehicle efficiency figures when importing a car between the UK and US.
Cross-check manufacturer MPG claims published in different markets.
Convert road-trip fuel consumption estimates between UK and US gallon standards.
Understand why a UK car rated at 50 MPG appears more efficient than a US 40 MPG car.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu