mpg (UK)

Miles per imperial gallon, the fuel economy figure UK drivers use. The bigger gallon makes UK figures read higher than US ones.

Last reviewed

mpg (UK) measures miles per imperial gallon of 4.54609 liters. UK official fuel consumption figures are WLTP-based, and UK labels show consumption in both mpg and L/100 km.

Two conversion facts cover almost every situation. From metric: mpg (UK) equals 282.480936 divided by the L/100 km figure, so 6 L/100 km is about 47 mpg (UK). Against American figures: because the imperial gallon holds roughly 20% more than the US gallon, the same car reads about 20% higher in UK mpg than in US mpg, a classic source of confusion.

CarPairly guards against exactly that mix-up by storing consumption in L/100 km for each test cycle and labeling every displayed figure with its gallon. When you read a review, check which country it comes from before judging the number.

Differs by market

The imperial gallon is 4.54609 L versus 3.785411784 L for the US gallon. Conversion: mpg (UK) = 282.480936 ÷ L/100 km, computed from the stored WLTP consumption value.

  1. NIST SP 811, Appendix B.8, conversion factors listed alphabetically (gallon)
    NIST Accessed
  2. NIST SP 811, Appendix B.9, conversion factors by quantity (mile, miles per gallon)
    NIST Accessed
  3. Vehicle Certification Agency, The Worldwide Harmonised Light Vehicle Test Procedure (WLTP)
    UK Vehicle Certification Agency Accessed
  4. Vehicle Certification Agency, Fuel Consumption Labelling
    UK Vehicle Certification Agency Accessed

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