How this calculator works
Gross saving is litres purchased multiplied by the pence-per-litre difference. The detour cost uses extra driving miles, UK MPG and the chosen fuel price. Net saving is the first value minus the second.
This estimates fuel money only. Extra time, parking costs, traffic, station queues and different fuel grades may also affect your decision.
Common questions
Why use the extra miles rather than distance to station?
If the cheaper pump lies along your normal route, only count the miles added by leaving and rejoining that route.
What if both stations charge the same price?
There is no price saving to offset a detour. The extra journey generally makes the cheaper-station option worse.