Calculate the running cost of any appliance from its wattage
Understanding how much individual appliances cost to run is one of the most effective ways to manage your household electricity bill. In the UK, where energy costs have been a major concern since the price rises of 2022-2023, knowing which appliances are the biggest consumers helps you make informed decisions about usage patterns and potential upgrades. The Ofgem Energy Price Cap sets the maximum unit rate that energy suppliers can charge for electricity. As of the current cap period, the rate is approximately 24.5p per kWh, though this changes quarterly. On top of the unit rate, households pay a daily standing charge (currently around 61p per day) just for being connected to the grid. This calculator focuses on the unit rate cost of running specific appliances. Every electrical appliance has a wattage rating, usually printed on a label or in the manual. This tells you how much power it draws when in active use. Common household appliances range enormously: an LED bulb might use just 10W, while a kettle draws 2,000-3,000W. The cost to run an appliance depends on its wattage, how many hours you use it, and the current electricity rate. Many modern appliances also draw a small amount of power in standby mode, which adds up across dozens of devices -- the average UK household spends GBP 50-80 per year on standby power alone.
To calculate the running cost of any appliance: 1. Enter the appliance wattage. This is found on the appliance label, in the manual, or by searching online. Common values: kettle 2000-3000W, washing machine 500-2500W, TV 50-200W, LED bulb 5-15W, oven 2000-2500W, fridge 100-200W (compressor cycles on and off). 2. Set the hours per day you use the appliance. For devices that cycle (like fridges), estimate the actual active time -- a fridge compressor typically runs about 8 hours per day despite being plugged in 24/7. 3. Set the days per week you use it. A washing machine might be 3-4 days, while a fridge runs all 7 days. 4. Adjust the electricity rate if your tariff differs from the Ofgem cap default. Check your latest energy bill for your exact unit rate. 5. Optionally enter standby power consumption for devices that remain plugged in. TVs, games consoles, and set-top boxes typically draw 1-15W on standby. 6. View the cost breakdown across daily, weekly, monthly, and yearly periods, plus the carbon footprint of your usage.
The electricity cost calculation converts wattage to kilowatt-hours (kWh) and multiplies by the unit rate: Daily kWh = (wattage x hours per day + standby watts x remaining hours) / 1000 Weekly kWh = daily kWh x days per week Monthly kWh = weekly kWh x 52 / 12 Yearly kWh = weekly kWh x 52 Cost in pence = kWh x rate (p/kWh) For example, a 2000W kettle used for 30 minutes per day at 24.5p/kWh: daily kWh = (2000 x 0.5) / 1000 = 1.0 kWh. Daily cost = 1.0 x 24.5 = 24.5p. Yearly cost = 1.0 x 7 x 52 x 24.5 = 8918p = GBP 89.18. The CO2 calculation uses the UK grid carbon intensity factor of 0.207 kg CO2 per kWh, which reflects the mix of generation sources (gas, wind, nuclear, solar) on the national grid. This figure has been declining as the UK adds more renewable capacity.
The UK government offers several schemes to help with energy costs. The Warm Home Discount provides GBP 150 off electricity bills for eligible low-income households. The Energy Company Obligation (ECO) scheme funds insulation and heating improvements. Smart meters, available free from your energy supplier, help you monitor usage in real time and identify which appliances are driving your bill.