US MPG to UK (Imperial) MPG Converter
Convert US miles per gallon to UK (Imperial) miles per gallon. Formula: MPG (UK) = MPG (US) × 1.20095. The Imperial gallon is about 20% larger than the US gallon.
How to Convert US MPG to UK MPG
The conversion is linear — the difference is entirely in the size of the gallon, not in the miles.
- MPG (UK) = MPG (US) × 1.20095042
The factor 1.20095 is the exact ratio between the Imperial gallon (4.54609 L) and the US gallon (3.785411784 L).
US MPG ↔ UK MPG Reference Table
Common fuel-economy values expressed in both gallon systems. Click any US MPG for a dedicated page.
| MPG (US) | MPG (UK) | L/100km | km/L | Category |
|---|---|---|---|---|
| 15 | 18.0 | 15.7 | 6.38 | Poor |
| 20 | 24.0 | 11.8 | 8.50 | Below average |
| 25 | 30.0 | 9.41 | 10.6 | Average |
| 30 | 36.0 | 7.84 | 12.8 | Average |
| 35 | 42.0 | 6.72 | 14.9 | Very good |
| 40 | 48.0 | 5.88 | 17.0 | Very good |
| 50 | 60.0 | 4.70 | 21.3 | Excellent |
| 60 | 72.1 | 3.92 | 25.5 | Excellent |
Common US MPG to UK MPG Conversions
| MPG (US) | MPG (UK) | L/100km |
|---|---|---|
| 10 MPG | 12.0 | 23.5 |
| 11 MPG | 13.2 | 21.4 |
| 12 MPG | 14.4 | 19.6 |
| 13 MPG | 15.6 | 18.1 |
| 14 MPG | 16.8 | 16.8 |
| 15 MPG | 18.0 | 15.7 |
| 16 MPG | 19.2 | 14.7 |
| 17 MPG | 20.4 | 13.8 |
| 18 MPG | 21.6 | 13.1 |
| 19 MPG | 22.8 | 12.4 |
| 20 MPG | 24.0 | 11.8 |
| 21 MPG | 25.2 | 11.2 |
| 22 MPG | 26.4 | 10.7 |
| 23 MPG | 27.6 | 10.2 |
| 24 MPG | 28.8 | 9.80 |
| 25 MPG | 30.0 | 9.41 |
| 26 MPG | 31.2 | 9.05 |
| 27 MPG | 32.4 | 8.71 |
| 28 MPG | 33.6 | 8.40 |
| 29 MPG | 34.8 | 8.11 |
| 30 MPG | 36.0 | 7.84 |
| 31 MPG | 37.2 | 7.59 |
| 32 MPG | 38.4 | 7.35 |
| 33 MPG | 39.6 | 7.13 |
| 34 MPG | 40.8 | 6.92 |
| 35 MPG | 42.0 | 6.72 |
| 36 MPG | 43.2 | 6.53 |
| 37 MPG | 44.4 | 6.36 |
| 38 MPG | 45.6 | 6.19 |
| 39 MPG | 46.8 | 6.03 |
| 40 MPG | 48.0 | 5.88 |
| 41 MPG | 49.2 | 5.74 |
| 42 MPG | 50.4 | 5.60 |
| 43 MPG | 51.6 | 5.47 |
| 44 MPG | 52.8 | 5.35 |
| 45 MPG | 54.0 | 5.23 |
| 46 MPG | 55.2 | 5.11 |
| 47 MPG | 56.4 | 5.00 |
| 48 MPG | 57.6 | 4.90 |
| 49 MPG | 58.8 | 4.80 |
| 50 MPG | 60.0 | 4.70 |
| 51 MPG | 61.2 | 4.61 |
| 52 MPG | 62.4 | 4.52 |
| 53 MPG | 63.7 | 4.44 |
| 54 MPG | 64.9 | 4.36 |
| 55 MPG | 66.1 | 4.28 |
| 60 MPG | 72.1 | 3.92 |
| 65 MPG | 78.1 | 3.62 |
| 70 MPG | 84.1 | 3.36 |
| 80 MPG | 96.1 | 2.94 |
| 100 MPG | 120.1 | 2.35 |
Frequently Asked Questions
How do I convert US MPG to UK MPG?
Multiply your US MPG value by 1.20095. Example: 30 MPG (US) × 1.20095 = 36.0 MPG (UK). The factor comes from the gallon ratio: 4.54609 L ÷ 3.785411784 L = 1.20095.
Why is UK MPG higher than US MPG for the same car?
The Imperial (UK) gallon is about 20% larger than the US gallon (4.546 L vs 3.785 L). More litres per gallon means more miles per gallon for the same real-world fuel economy — even though the car is no more efficient.
Are US and UK MPG measured on the same test cycle?
No. US figures come from the EPA 5-cycle test. UK figures follow WLTP (Worldwide Harmonised Light Vehicle Test Procedure). Even after converting units, there can be small differences because the test conditions differ. This calculator handles only the unit conversion.
Which MPG is on my UK car’s window sticker?
UK window stickers show MPG (UK / Imperial). US EPA window stickers show MPG (US). If you import a US car to the UK, multiply its MPG figure by 1.20095 to get the equivalent UK figure for comparison.
Related Fuel Economy Converters
Why US and UK MPG Figures Differ
Every few years a traveller spots a British car brochure quoting 55 MPG and wonders why the American equivalent barely manages 46 MPG. Nothing has changed about the car — only the gallon. The Imperial (UK) gallon is 4.54609 litres; the US gallon is 3.785411784 litres. That makes the Imperial gallon about 20.1% larger, so any car’s MPG figure is 20.1% higher when expressed in UK gallons.
The formula is simply MPG (UK) = MPG (US) × 1.20095. The factor 1.20095 is not rounded — it is the exact ratio 4.54609 ÷ 3.785411784.
Historical Origin of the Two Gallons
The US gallon descends from the Queen Anne Wine Gallon of 1707 — 231 cubic inches — which British colonial traders were already using for wine and rum. Britain itself reformed its units in 1824, defining the new Imperial gallon as the volume of 10 pounds of distilled water at 62°F. That came out to 4.54609 L. The Americans, already independent, kept the old wine gallon. Two centuries later, the split persists.
Quick Reference: Common US MPG Values in UK Terms
- 20 MPG (US) → 24.0 MPG (UK) — large SUV or pickup
- 25 MPG (US) → 30.0 MPG (UK) — midsize SUV
- 30 MPG (US) → 36.0 MPG (UK) — midsize sedan
- 35 MPG (US) → 42.0 MPG (UK) — compact car
- 40 MPG (US) → 48.0 MPG (UK) — efficient compact or hybrid
- 50 MPG (US) → 60.0 MPG (UK) — hybrid or plug-in hybrid
- 60 MPG (US) → 72.1 MPG (UK) — top-tier hybrid or PHEV
When You Need This Conversion
Three common situations call for a US-to-UK MPG conversion:
- Importing a US vehicle. DVLA registration and UK insurance quotes reference Imperial MPG. The US Monroney label needs to be translated before you can compare to the UK brochure figure.
- Reading US-written car reviews. Magazines like Car and Driver or MotorTrend quote MPG in US gallons. To match against your local petrol-station experience, convert the figure to UK MPG first.
- Comparing cross-Atlantic fuel costs. A 30-MPG American pickup is not as thrifty as a 30-MPG British hatchback — the pickup is closer to 36 MPG on Imperial measurement, but still burns more real fuel per mile than a small diesel.
MPG Differences Are Not Efficiency Differences
A car rated at 30 MPG (US) is not secretly 20% less efficient than one rated at 36 MPG (UK) — they are the same car in different clothes. The only way to compare efficiency across systems is to convert to a unit-neutral metric like L/100km. Both 30 MPG (US) and 36 MPG (UK) equal 7.84 L/100km.
Full Conversion Table
Need a printable reference? See the full US MPG to UK MPG conversion table with pre-calculated values, CSV download, and print-friendly layout.
