Electricity Cost Calculator (UK)

Your electricity spend is mostly: how many kWh you use × price per kWh, plus a daily fee(the standing charge) that shows up even in summer when the heating's off. Almost every domestic tariff is built that way, which is why your bill has both numbers.

If you know monthly kWh from a bill or app, you can sketch annual cost yourself: multiply kWh by 12, multiply by the unit rate, add standing charge × 365 (all in pence, then convert to pounds). That same maths is what our Octopus comparison runs for you automatically — we fetch today's published rates for your region so you don't copy them by hand.

Step 1: Find your monthly usage (kWh)

Bills usually show kWh for the period. If you only have a quarter, divide by three; if you have a year, divide by twelve. A rough guess still helps you see which tariffs are in the same ballpark — refine later when you have a proper read.

Step 2: Understand unit rate vs standing charge

• Unit rate: billed per kWh. Higher usage makes this more important.
• Standing charge: billed per day. Lower usage makes this more important because it’s fixed.

Step 3: Estimate annual cost

This is the same approach we use in the Octopus Savings Calculator — but instead of asking you to copy unit rates manually, we fetch live rates and standing charges directly from Octopus’s official API for your postcode region.

If Octopus looks cheaper

Confirm the live product on octopus.energy, then switch there. Many people use a referral link for account credit (amount and rules set by Octopus — check their site).