FAQs

What do Octopus, EPEX-30 and N2EX mean on a slot?

Octopus set Agile prices from the day-ahead wholesale auction, but publish them later in the day. Before that, 48 shows an estimate worked out from the same wholesale data, labelled so you can see it isn't official yet:

• N2EX — an early, rougher estimate from N2EX day-ahead wholesale prices, available from around 09:50. This is the least certain figure of the day and can move once firmer data arrives.
• EPEX-30 — a firmer estimate from the EPEX 30-minute wholesale auction, available from around 16:00. It's the same underlying data Octopus's own formula uses, so it's usually very close to the real price.
• Octopus — Octopus's own published price.

On the chart, solid bars are Octopus prices, lighter bars are EPEX-30 and outlined bars are N2EX. Hover over any bar to see its time, price and source.

Why might the cheapest window change later on?

If the window it finds includes any N2EX slots, 48 shows a warning. Those are the least certain estimates, and the window could shift once the EPEX-30 or Octopus price settles. EPEX-30 slots are reliable enough not to trigger the warning.

How is the cheapest window's cost worked out?

It assumes a steady 1 kW load, so 1 kWh every hour across the window you choose — the kind of load you'd get from an immersion heater or a fixed-rate charger. If your appliance draws power unevenly (most EV chargers, or batteries with their own charge curve), the real cost will differ. The window itself is still the cheapest available; only the cost figure may not match.

What is Plunge watch?

Agile prices sometimes drop below zero, usually when it's very windy and demand is low. During those slots you're paid to use electricity. Plunge watch lists any below-zero slots coming up, and they show in blue on the chart, below the zero line.

What is the dashed SVT line?

It's Octopus's standard variable rate (Flexible Octopus) for your region, including VAT, refreshed daily. Any slot below the line is cheaper than you'd pay on the standard tariff at that moment.

Are the prices VAT inclusive?

Yes. The prices on the site include VAT. The API gives both the inc-VAT and exc-VAT figures.

Why is it called 48?

There are 48 half-hour slots in a day, and Agile has a different price for every one of them.

Is 48 part of FPRates?

Yes, 48 is an FPRates project. FreePhase stays at fprates.online. The two are kept completely separate, with their own terms, contact form and API, so there's no risk of mixing up which tariff you're looking at.

Which regions are covered?

All 14 GB electricity regions. Choose yours from the Region menu at the top of any page and 48 will remember it. If you're not sure which region you're in, check your Octopus bill or account.

Is 48 an official Octopus service?

No. 48 is independent and is not affiliated with, endorsed by, or connected to Octopus Energy in any way. Octopus and Agile are trademarks of Octopus Energy. 48 uses publicly available data.

Is it free?

Yes, completely. If you find it useful, you can buy me a coffee to help with server costs, but there's no obligation whatsoever.

Is there an API?

Yes. There's a free JSON API in the standard Octopus/Kraken format used by home-automation tools like predbat, plus a date-range endpoint for pulling prices into Excel. See the API documentation.

Does 48 use cookies?

One small cookie, stored only on your device, remembers your chosen region. The contact form also sets a short-lived cookie to check the anti-spam sum. Neither tracks you, is shared, or leaves your browser, and there are no advertising or analytics cookies.