Glossary
Break-Even Distance
Direct Answer / TL;DR
What is Break-Even Distance?
The maximum distance you can travel to a cheaper fuel station before the fuel cost of the detour wipes out the price saving entirely. If the station is closer than the break-even distance, you save money; if it's farther, you don't.
Why does it matter for UK drivers?
Break-even distance is the core insight behind WorthThePump. It answers the question: 'How far away can this cheaper station be before the trip costs as much as I save?'
The formula is: break-even distance (miles) = (price difference per litre × fill volume in litres) ÷ cost per mile. Cost per mile is calculated as (price per litre × 4.546) ÷ MPG.
A worked example: you plan to fill 45 litres, the cheap station is 4p/L cheaper, and your car does 40 MPG. Cost per mile at 145p/L: (145 × 4.546) ÷ 40 = 16.5p/mile. Gross saving: 45 × 4p = 180p = £1.80. Break-even distance: 180p ÷ 16.5p = 10.9 miles one-way (21.8 miles round trip). So if the station is less than 10.9 miles away on a detour, the trip is worth it.
Break-even distance is highly sensitive to MPG. For a 55 MPG hybrid on the same scenario, cost per mile drops to 12p, and break-even extends to 15 miles — the driver can go further to chase a saving. For a 20 MPG Land Cruiser, cost per mile is 33p and break-even is only 5.5 miles.
This is why generic 'cheapest station near you' apps don't tell the full story. A supermarket 8 miles away might show the cheapest price in the area — but for a van driver doing 22 MPG, the detour may actually cost more than they save.
WorthThePump calculates break-even distance per station based on your specific vehicle's MPG and the actual road geometry, and displays it alongside the net saving for each station in the results.
Related terms
Further reading
Now you know what Break-Even Distance means —
find out if your nearest cheap station is actually worth the trip.