How the figures are calculated

Every figure here is built from the Fuel Finder file published by the Department for Energy Security and Net Zero, with the service operated by VE3. The file is published twice a day and lists current prices and forecourt details. We take the file, keep its bytes privately, and publish only figures calculated from it. The file itself is not republished, and no feed, download or page carries a row from it.

A day is a London calendar day, and a station contributes its last accepted price for each fuel grade on that day. The same file arriving twice does not create a second day.

An area median is the middle of the daily medians inside the window, which keeps one busy day from dominating. A day enters only if at least three stations reported that grade. The spread is the middle of the daily differences between the highest tenth and the lowest tenth, and it needs five stations on each included day. A brand figure compares that brand with the other stations in the same district on matching days, and both groups need three stations on a day.

Two measures are deliberately absent. The age of a price is not calculated, because the meaning of the publisher's timestamp is not established. A ranking of stations is never published at any size.

Worked example, CR0. Stations reporting E10 petrol: 14 stations. Three scheduled collections of three due. They hold one distinct publisher release.

No published count of reporting stations for the same moment was found, so completeness is unverified.