21 MPG to Miles per Litre
| 21 MPG (UK) | = | 4.62 miles per litre |
| 21 MPG (UK) | = | 13.5 L/100km |
| 21 MPG (UK) | = | 7.43 km/L |
| 21 MPG (UK) | = | 17.5 MPG (US) |
How to Convert MPG to Miles per Litre
The conversion is linear: a litre is a fixed fraction of a gallon, so dividing MPG by the litres-per-gallon constant gives miles per litre directly.
- MPL = MPG (UK) ÷ 4.54609
- MPL = MPG (US) ÷ 3.785411784
Applying the formula to 21 MPG (UK): 21 ÷ 4.54609 = 4.62 miles per litre.
Is 21 MPG (UK) good?
21 MPG (UK) is considered Below average — large SUV or older vehicle. That works out to 4.62 miles per litre, 13.5 L/100km, or 7.43 km/L. In US terms, 21 MPG (UK) = 17.5 MPG (US).
Need a different value? Use our MPG to Miles per Litre Converter.
Similar Conversions
| MPG (UK) | MPL | L/100km |
|---|---|---|
| 16 MPG | 3.52 | 17.7 |
| 17 MPG | 3.74 | 16.6 |
| 18 MPG | 3.96 | 15.7 |
| 19 MPG | 4.18 | 14.9 |
| 20 MPG | 4.40 | 14.1 |
| 22 MPG | 4.84 | 12.8 |
| 23 MPG | 5.06 | 12.3 |
| 24 MPG | 5.28 | 11.8 |
| 25 MPG | 5.50 | 11.3 |
| 26 MPG | 5.72 | 10.9 |
Related Fuel Economy Converters
Miles per Litre to MPG
Reverse conversion: miles per litre to miles per gallon (UK and US).
MPG (UK) to L/100km
Convert Imperial MPG to litres per 100 km for European comparisons.
MPG to L/100km
Miles per gallon (US/UK) to litres per 100 km.
MPG Calculator
Calculate your car’s MPG from distance and fuel used.
Conversion factors verified against NIST, BIPM
Based on SI definitions (BIPM).
Last reviewed: March 2026
