How we measure
Every figure on this site can be traced back to the responses operators published. These are the rules we apply.
What we collect
Every minute (every two minutes where an operator's interface asks for it) we fetch the status of each public charge point from the open data operators publish: their OCPI interfaces and national access points. In the United Kingdom, operators publish this data under the Public Charge Point Regulations 2023. Each response is stored exactly as received, with when and how we fetched it.
We never edit the source
Operators' data is sometimes wrong: coordinates in the wrong country, missing fields, statuses that contradict each other. We never change what they published. Where we correct or interpret something, we do it in our own layer and record it as a note next to the original.
Status, in two parts
Standards describe status differently. We translate each into two questions: is the charge point in service (or faulted, unavailable, planned, removed), and is it free (or occupied, reserved, blocked)?
Definitions
- Available
- Time in service, divided by the time we had data for. Time without data is not counted as down: that would blame an operator for our gap or theirs.
- Out of order
- Time reported faulted, divided by the time we had data for.
- Coverage
- The time we had data for, divided by the time in the period, across all charge points. It's always shown next to availability.
- No data
- An observation counts for twice the interval at which its source publishes (two minutes for a feed fetched every minute). Beyond that, the time is "no data". Whole days without data are shown as missing, never estimated, and filled in if the data arrives later.
- Days
- Local days: UK time for UK sources, so the days the clocks change have 23 or 25 hours. Months, quarters and years are built from days.
Recalculation
Late data, corrections and improvements to our methods are applied by recalculating from the stored responses. A recalculated day replaces the old one; nothing is ever counted twice.