Electricity Cost Calculator

To calculate energy costs, you need three things: the power consumption in watts (W), hours of usage per day, and your electricity rate per kWh. The formula is: (Watts x Hours per day x Days) ÷ 1000 x Cost per kWh. For example, a 2000W appliance used for 2 hours daily at 26.32p/kWh (the Ofgem price cap for October to December 2026) costs: (2000 x 2 x 30) ÷ 1000 x 0.2632 = £31.58 per month.

A kilowatt-hour (kWh) is a unit of energy representing the amount of electricity used by a 1000-watt appliance running for one hour. For example, a 100W light bulb running for 10 hours uses 1 kWh (100W x 10 hours ÷ 1000). Your electricity bill charges you per kWh used, typically around 26p to 27p per kWh in the UK, set by the Ofgem price cap.

Check the appliance label or manual - power consumption is usually listed in watts (W) or kilowatts (kW). Alternatively, use a plug-in energy monitor (£15-£30) that measures actual consumption. Some appliances also have variable consumption - for example, fridges cycle on and off, so average usage is lower than maximum power. Modern smart plugs often include energy monitoring features.

The biggest energy consumers are usually: electric heating and hot water (40-50% of bills), washing machines and tumble dryers (14%), lighting (11%), cooking (8-10%), fridges and freezers (7%), and TVs/electronics (5-7%). Heating and hot water dominate in winter, while in summer, appliances like tumble dryers and air conditioning (if present) can be significant. Standby power from devices left plugged in accounts for about 9-16% of household electricity use.

Standby power (also called phantom or vampire power) can cost £45-£80 per year for an average UK household. Common culprits include TVs (£10-15/year), games consoles (£12-20/year), set-top boxes (£8-12/year), computers (£5-10/year), and phone chargers (£2-5/year). Turning devices off at the socket or using smart plugs with timers can significantly reduce this waste.

If you have an Economy 7 or Economy 10 tariff, yes - you get cheaper electricity during off-peak hours (usually 11pm-8am). Off-peak rates can be 50-60% cheaper than peak rates, making it worthwhile to run dishwashers, washing machines, and charge devices overnight. However, peak rates on these tariffs are higher than standard rates, so they only save money if you can shift significant usage to off-peak times. Smart meters and time-of-use tariffs are making flexible pricing more common.

Energy-efficient appliances can save 20-70% on running costs compared to older models. For example, an A+++ rated fridge uses £35/year vs £65/year for an A-rated model. LED bulbs use 80-90% less energy than incandescent bulbs. Modern washing machines use 50% less water and energy than 15-year-old models. While efficient appliances cost more upfront, they typically pay for themselves within 2-5 years through energy savings, and the savings continue for their entire lifespan (10-15 years).

The most effective strategies are: 1) Improve insulation (loft, walls, draught-proofing) to reduce heating needs, 2) Switch to LED bulbs throughout the home, 3) Turn heating down by 1°C (saves ~£60-90/year), 4) Use appliances efficiently (full loads, lower temperatures, air-dry when possible), 5) Turn off devices at the plug rather than standby, 6) Use smart thermostats and timers to heat only when needed, and 7) Compare energy suppliers regularly - switching can save £200-400/year.

Yes. Choose Gas in the fuel selector and use the gas unit rate. Gas appliances are usually rated in kW, so a 24kW boiler running for one hour uses about 24 kWh. At the October 2026 gas cap of 7.97p per kWh, that is roughly £1.91 an hour. Gas is usually much cheaper per kWh than electricity, which is why heating with gas costs less than electric heating.

A standing charge is a fixed daily amount you pay to be connected to the grid, no matter how much energy you use. In October to December 2026 the average is 54.83p a day for electricity and 29.68p a day for gas, about £309 a year together before you use any energy. The calculator adds your standing charges so you can see the full cost.

Smart meters provide real-time energy usage data and eliminate estimated bills, helping you identify wasteful appliances and change habits. They're free to install and enable time-of-use tariffs that can save money if you can shift usage to off-peak times. However, they don't automatically save money - you must actively use the data to change behavior. First-generation SMETS1 meters can lose smart functionality if you switch suppliers, but newer SMETS2 meters work with all suppliers.

Heating water is one of the biggest energy expenses, costing an average household £200-400 per year. An electric shower uses 7-10 kW and costs £0.50-1.00 per 10-minute shower. Immersion heaters use 3-6 kW and cost £1-2 per hour. To reduce costs: take shorter showers, install water-efficient showerheads, insulate your hot water tank, fix dripping taps, only boil the water you need in kettles, and consider a hot water timer to heat water only when needed. Gas water heating is typically 3-4x cheaper than electric.

Under the Ofgem price cap for October to December 2026 the average electricity unit rate is 26.32p per kWh, plus a standing charge of about 54.83p a day. Gas is capped at 7.97p per kWh with a 29.68p daily standing charge. Your actual rate depends on your region and tariff - enter your own rate above for exact appliance costs. A useful shortcut: 100 kWh of electricity costs about £26.32 at the cap.

An appliance electricity cost calculator converts an appliance's power rating in watts and its hours of use into a running cost in pounds, using your electricity unit rate. The formula is (watts x hours x days) ÷ 1000 x price per kWh. This electricity cost calculator does that for multiple appliances at once and adds standing charges, so you can compare an air fryer, oven, tumble dryer or EV charger and see which costs the most to run per year.