Electricity Bill Calculator UK
Estimate an appliance electricity units and cost from its wattage, usage hours and tariff.
How it works
A discount reduces the original price by a percentage. The saving is the price times the discount; the sale price is what remains.
Sale price = Price × (1 − discount%)Frequently asked questions
How is electricity cost calculated?
Energy used in kWh times your unit rate, plus a daily standing charge. kWh = watts × hours ÷ 1,000.
What is a kilowatt-hour?
The energy used by a 1,000-watt appliance running for one hour — the unit your supplier bills you by.
What is a typical UK unit rate?
Around 25p per kWh under the Ofgem price cap, though it varies by tariff, region and over time.
What is a standing charge?
A fixed daily fee that applies regardless of how much energy you use, covering the cost of supplying your home.
What is the Ofgem price cap?
A limit set by the regulator on the unit rate and standing charge suppliers can charge on standard variable tariffs.
Which appliances cost the most to run?
High-power devices used for long periods — electric heating, hot water, tumble dryers and ovens — dominate most bills.
How your electricity cost is worked out
Electricity is billed by the kilowatt-hour (kWh) — the energy of a 1,000-watt appliance running for one hour. Your cost is the kWh used multiplied by your unit rate, plus a daily standing charge. This calculator turns an appliance’s wattage and run time into a cost.
From watts to cost
Energy used: kWh = watts × hours ÷ 1,000. A 2,000-watt heater for 3 hours uses 6 kWh. At a unit rate of around 25p per kWh (UK rates sit under the Ofgem price cap and vary by tariff and region) that is about £1.50.
Unit rate and standing charge
A UK bill has two parts: a per-kWh unit rate for the energy you use, and a fixed daily standing charge that applies regardless of usage. The Ofgem price cap limits the rates suppliers can charge on standard variable tariffs, but fixed deals may differ.
To cut costs, focus on high-power appliances used for long periods — heating, hot water and tumble dryers dominate most bills. Check your own unit rate and standing charge on your latest statement, as they vary by tariff and region.
Results are estimates for general guidance in United Kingdom and may not reflect the latest local rates, fees or rules. Check official sources before making decisions.