About halfhourly.uk
Great Britain's electricity market settles in half-hourly periods — 48 of them a day. On a tracker tariff like Octopus Agile the price you pay changes with each one, following wholesale costs. This site shows those rates for every region, as soon as they are published.
It covers gas as well as electricity, and every Octopus tariff shape: half-hourly (Agile), time-of-use (Go, Cosy, Flux) and flat (Flexible, Fixed). Whatever the shape, rates are expanded onto the same half-hourly grid, so any two tariffs can be compared slot for slot.
Where the data comes from
Unit rates are read from the public Octopus Energy REST API, which needs no authentication for tariff pricing. This site caches responses for a few minutes so it stays fast and does not hammer the upstream service. Tomorrow's rates are usually published around 16:00 UK time.
Unit rates are shown in pence per kilowatt-hour and standing charges in pence per day, both including VAT, on the monthly direct debit payment method where a tariff offers more than one.
Tariff products are discovered from the API rather than hardcoded, because Octopus rotates its fixed products every few months. New products appear here automatically.
Finding your region
Prices vary by Grid Supply Point group. Yours is determined by the first two digits of the MPAN printed on your electricity bill — the number in the box marked "Supply Number".
| Code | Region | Network operator |
|---|---|---|
| A | Eastern England | UK Power Networks |
| B | East Midlands | National Grid Electricity Distribution |
| C | London | UK Power Networks |
| D | North Wales & Merseyside | SP Energy Networks |
| E | West Midlands | National Grid Electricity Distribution |
| F | North East England | Northern Powergrid |
| G | North West England | Electricity North West |
| H | Southern England | Scottish & Southern Electricity Networks |
| J | South East England | UK Power Networks |
| K | South Wales | National Grid Electricity Distribution |
| L | South West England | National Grid Electricity Distribution |
| M | Yorkshire | Northern Powergrid |
| N | Southern Scotland | SP Energy Networks |
| P | Northern Scotland | Scottish & Southern Electricity Networks |
Free JSON API
Everything on this site is available as JSON, CORS-enabled and with no key required. Please cache responses rather than polling faster than once a minute.
GET /api/products- Every tariff product, with its shape and term.
GET /api/now- Current and next half-hourly rate, plus the standing charge.
GET /api/prices?days=2- Every half-hourly rate for the next
daysdays (1–3). GET /api/cheapest?hours=3- The cheapest upcoming contiguous window of that length.
GET /api/compare?kwh=7.4- Every tariff ranked by estimated daily cost.
GET /api/regions- All GSP group codes and names.
GET /health- Service health, for uptime monitoring.
All endpoints accept region (a GSP group A–P or a full MPAN),
fuel (electricity or gas) and
product (a code from /api/products).
Example
curl -s "https://halfhourly.uk/api/cheapest?region=C&hours=3"Caveats
- This is an independent site with no connection to Octopus Energy.
- Rates shown are for single-register import tariffs (
E-1RandG-1R). - Economy 7 (
E-2R) and export tariffs are not covered yet. - Always confirm in your supplier's own app before making a decision that costs money.