Energy Cost Calculator is a free tool for UK households to estimate their electricity costs based on appliance usage. We help you understand how much your appliances cost to run and identify opportunities to reduce your energy bills.
Your electricity bill is determined by how much energy your appliances use (measured in kilowatt-hours, or kWh) and the unit rate charged by your supplier. The cost formula is straightforward: watts divided by 1,000, multiplied by hours of use, multiplied by the unit rate per kWh.
UK energy bills consist of two components: a unit rate for each kWh of electricity consumed, and a daily standing charge for being connected to the supply. Under the Ofgem price cap for 1 July to 30 September 2026, electricity on a standard variable tariff paid by direct debit is 26.11p per kWh and gas is 7.33p per kWh, with standing charges of 57.19p and 29.04p a day. Fixed deals sit outside the cap and rates vary by region.
The Ofgem price cap sets a maximum unit rate and standing charge that suppliers can charge customers on default tariffs. The cap is reviewed quarterly and is designed to protect consumers from excessive price increases. The calculator is pre-filled with the current capped electricity rate of 26.11p per kWh, published on Ofgem's unit rate page, and you can overwrite it with the rate from your own bill.
By entering the wattage and daily usage hours for each of your appliances, our calculator estimates your monthly and annual electricity costs. This can help you compare your estimated usage against your actual bills and identify which appliances are the most expensive to run.
All calculations are performed in your browser. Your appliance data is saved locally in your browser and is not transmitted to any server. Energy rates used are estimates and may differ from your actual tariff.
This calculator provides estimates for informational purposes only. Actual energy costs depend on your specific tariff, usage patterns, and supplier. We are not affiliated with Ofgem or any energy supplier.