MPG calculator
Your real fuel economy from one tank - in UK miles per gallon or litres per 100 km - and what every mile costs you.
For a true figure: fill to the brim and reset the trip, drive as normal, then brim it again. The trip reading and the litres that second fill takes are your numbers.
Your fuel economy
Enter the miles and the litres, and your MPG shows here.
Let RoadVerdict do this for every tank
Log a fill-up in seconds and your real MPG is worked out from every full tank, with your fuel spend and cost per mile alongside. When you sell, the whole history goes with the vehicle.
How to measure your real MPG
- Fill the tank to the brim - until the pump clicks off - and reset your trip meter.
- Drive as you normally would. The more miles before the next fill, the truer the figure.
- Fill to the brim again, at the same pump if you can, and note how many litres it takes.
- Enter the trip reading and those litres above. That's your real MPG for that tank.
The economy readout on your dashboard is the vehicle's own estimate. Brim to brim measures what actually went in - which is also how RoadVerdict works out the average from your logged fill-ups.
UK MPG and US MPG aren't the same
A UK gallon is 4.546 litres; a US gallon is 3.785. The same tank therefore gives a number about a fifth higher in UK MPG. If a figure you've read online looks disappointing, check which gallon it uses: 40 US mpg is 48 UK mpg. The calculator shows both.
Converting MPG and litres per 100 km
The two run in opposite directions - more miles per gallon is better, fewer litres per 100 km is better - so one isn't a fixed multiple of the other. To convert either way, divide 282.5 by the number you have.
| MPG (UK) | L/100km |
|---|---|
| 30 | 9.4 |
| 40 | 7.1 |
| 50 | 5.6 |
| 60 | 4.7 |
| 70 | 4.0 |
| 80 | 3.5 |
Why yours won't match the official figure
Official figures come from a standard laboratory test, which makes them a fair way to compare one model with another. What you actually get depends on your roads, your speed, the load you carry, the weather and how often the engine starts from cold - so your own brim-to-brim figure is the one to budget with.