MPG Converter
Convert UK MPG to litres per 100km, km per litre and US MPG.
Your result
Updates as you type. Based on 2025/26 UK figures where relevant.
How this is worked out
UK gallons are bigger than US gallons, so the same car shows a higher UK MPG. L/100km = 282.48 ÷ UK MPG.
Tips
- UK MPG uses imperial gallons (4.546 litres), which differ from US gallons.
- HMRC's approved mileage rate is 45p per mile for the first 10,000 business miles.
- Home EV charging on an off-peak tariff is usually far cheaper than public rapid chargers.
Guides for this calculator
- How to Calculate MPG Conversions in the UK: Step-by-Step Guide
- MPG Conversions: Common Mistakes, Tips and FAQs
More motoring calculators
Frequently asked questions
How does the mPG Converter work?
UK gallons are bigger than US gallons, so the same car shows a higher UK MPG. L/100km = 282.48 ÷ UK MPG.
What MPG should I use?
Use your real-world figure from your car's trip computer if you can; official figures are often optimistic.
Can I claim for commuting miles?
No. Normal commuting to a permanent workplace doesn't count as business mileage.
How often do HMRC mileage rates change?
Rarely. The 45p rate has been unchanged for many years, but always check GOV.UK.
This calculator gives an estimate for general information. It isn't financial, tax, legal or medical advice. Check official figures on GOV.UK or NHS.uk, or speak to a qualified adviser.