40 US MPG to UK MPG
| 40 MPG (US) | = | 48.0 MPG (UK / Imperial) |
| 40 MPG (US) | = | 5.88 L/100km |
| 40 MPG (US) | = | 17.0 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 40 MPG (US): 40 × 1.20095 = 48.0 MPG (UK).
Is 40 MPG (US) good?
40 MPG (US) is considered Very good — typical of efficient sedans and compact cars. In Imperial terms, that’s 48.0 MPG (UK). In metric terms, 5.88 L/100km or 17.0 km/L.
Need a different value? Use our US MPG to UK MPG Converter.
Similar Conversions
| MPG (US) | MPG (UK) | L/100km |
|---|---|---|
| 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 |
| 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 |
Related Fuel Economy Converters
Conversion factors verified against NIST, BIPM
Based on SI definitions (BIPM).
Last reviewed: March 2026
