Imperial MPG formula
MPG = miles ÷ (litres ÷ 4.54609)
Fill-to-fill method
Fill the tank, reset your trip counter, drive normally, then refill. The second fill gives a practical estimate of litres used over the measured miles.
Why it can differ
Real-world economy changes with traffic, temperature, tyres, load and driving conditions.
Open the real MPG calculator →
Last reviewed: 31 August 2026. See also methodology and sources.