Methodology and sources

Where the numbers come from

Every figure comes from Ofgem's "Benchmark Maximum Charges" cap tables. For each region and payment method they give the annual cost, excluding VAT, at nil consumption and at Ofgem's typical consumption. CapWatch UK stores those figures unchanged and derives the standing charge and unit rate from them:

• standing charge (p/day) = nil-use £ × 100 ÷ 365
• unit rate (p/kWh) = (typical-use £ − nil-use £) × 100 ÷ typical kWh
• annual bill = Σ fuels ((365 × standing charge + kWh × unit rate) ÷ 100) × (1 + VAT)

Rates are stored to four decimal places, excluding VAT. VAT is applied per fuel and per period when the site is built, because it can change between periods. Before publishing, an automated check confirms that every derived annual figure matches Ofgem's own to the penny, and that the average of the 14 regions matches Ofgem's published GB average unit rates and standing charges.

Typical use

For 1 July to 30 September 2026, Ofgem's typical consumption is 2,500 kWh of electricity and 9,500 kWh of gas a year (3,400 kWh for multi-register meters such as Economy 7). "Medium use" on this site means exactly those figures. Low and high use are not shown yet because we have not sourced figures for them from Ofgem.

VAT

Gas includes 5% VAT. Electricity includes 5% VAT.

Where VAT differs between two periods, the cap-week comparison includes VAT at each period's own rate and says so, because a before-and-after that ignored it would overstate the change.

Rounding

Rates are shown to two decimal places of a penny. Bills are calculated at full precision, then shown to the nearest pound. Monthly figures are the annual figure divided by 12.

Regions and postcodes

The cap has 14 regions in England, Scotland and Wales. Your postcode is sent from your browser straight to Octopus Energy's public grid-supply-point lookup to find your region. It never reaches our server, logs or analytics, and shared links contain the region, never the postcode. Where a postcode sits on a boundary, or can't be matched, you pick your region yourself.

Map

Region boundaries come from NESO's GB DNO licence areas, which NESO describes as approximate. Cost colours are fixed: green is 3% or more below the GB average, red 3% or more above, orange in between. The renewables view uses NESO's Carbon Intensity API, which estimates the generation mix of electricity consumed in each region. Estimated mix of electricity used in your region. It doesn't change your bill or your tariff.

Disclaimer

CapWatch UK shows the maximum unit rates and standing charges Ofgem allows suppliers to charge on standard variable (default) tariffs in England, Scotland and Wales. It is not your bill. What you pay depends on how much energy you use, your meter, how you pay and your tariff. If you are on a fixed tariff, the price cap does not change your rates. Bill figures use Ofgem's typical consumption assumptions and are rounded. This site is not financial advice and does not recommend any supplier or tariff. We are not affiliated with Ofgem. Contains public sector information licensed under the Open Government Licence v3.0. Figures last checked 22 September 2026.

Sources

• NESO: GIS boundaries for GB DNO licence areas (NESO Open Data Licence)
• NESO: Carbon Intensity API (CC BY 4.0)
• Octopus Energy developer docs (postcode to region)
• Ofgem: copyright and disclaimer

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