21 US MPG to UK MPG
| 21 MPG (US) | = | 25.2 MPG (UK / Imperial) |
| 21 MPG (US) | = | 11.2 L/100km |
| 21 MPG (US) | = | 8.93 km/L |
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).
Applying the formula to 21 MPG (US): 21 × 1.20095 = 25.2 MPG (UK).
Is 21 MPG (US) good?
21 MPG (US) is considered Below average — typical of full-size SUVs and pickup trucks. In Imperial terms, that’s 25.2 MPG (UK). In metric terms, 11.2 L/100km or 8.93 km/L.
Need a different value? Use our US MPG to UK MPG Converter.
Similar Conversions
| MPG (US) | MPG (UK) | L/100km |
|---|---|---|
| 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 |
| 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 |
Related Fuel Economy Converters
Conversion factors verified against NIST, BIPM
Based on SI definitions (BIPM).
Last reviewed: March 2026
