With electricity at over 24p per kWh, understanding what your appliances actually cost to run has never been more valuable. Many households spend hundreds of pounds a year on energy costs they do not fully understand. This guide explains the formula, gives real running cost examples for common appliances, and shares the most effective ways to cut your bills.
UK Energy Price Cap Rates (for calculations)
Ofgem's price cap unit rates for Q2 2025 (April–June 2025):
- Electricity: 24.50p per kWh
- Gas: 6.40p per kWh
- Electricity standing charge: ~61p/day
- Gas standing charge: ~31p/day
Use our Energy Cost Calculator to compute costs at the latest current rates automatically.
What Is a kWh?
A kilowatt-hour (kWh) is the energy used by a 1,000-watt device running for one hour. Your energy bill shows how many kWh you consumed, multiplied by the unit rate:
- A 100W light bulb running 10 hours = 1 kWh = ~24.5p
- A 2kW electric heater running 1 hour = 2 kWh = ~49p
- A 9kW electric shower for 10 minutes = 1.5 kWh = ~37p
The Running Cost Formula
Cost = (Watts ÷ 1,000) × Hours used × Unit rate (£) Example — 2kW heater for 3 hours: (2000 ÷ 1000) × 3 × £0.245 = £1.47 per session
Running Costs of Common Appliances (at 24.5p/kWh)
| Appliance | Typical wattage | Cost per hour | Monthly (daily use) |
|---|---|---|---|
| Electric shower (9kW, 10min) | 9,000W | £2.21/hr | ~£11/month |
| Tumble dryer | 2,500W | 61p/hr | ~£16/month |
| Electric oven (45 min use) | 2,200W | 54p/hr | ~£12/month |
| Dishwasher (1 cycle) | 1,500W | 37p/hr | ~£7/month |
| Washing machine | 2,000W | 49p/hr | ~£6/month |
| Electric heater | 2,000W | 49p/hr | ~£74/month (3hr/day) |
| Kettle (4 boils/day) | 3,000W | 73.5p/hr | ~£3/month |
| TV (55", LED) | 100W | 2.45p/hr | ~£2.20/month |
| LED bulb | 8W | 0.2p/hr | ~18p/month |
Most Effective Ways to Reduce Energy Bills
- Switch to a smart tariff with off-peak rates. Economy 7 / Octopus Agile and similar tariffs offer significantly cheaper electricity at night. Running dishwashers and washing machines at off-peak times can halve their energy cost.
- Reduce shower time. Each minute shorter saves approximately 4p (9kW shower at 24.5p/kWh). A household of 4 saving 2 minutes each per day = ~£47/year.
- Wash at 30°C instead of 40°C. Modern detergents clean effectively at lower temperatures. Uses up to 40% less energy per wash.
- Use a microwave for small meals. A microwave uses ~700-900W versus a 2200W oven — approximately 4× more efficient for reheating or small portions.
- Full loads only. Dishwashers and washing machines use similar energy for half or full loads. Only run when full.
- Draught-proof doors and windows. Reducing heat loss through draughts is one of the cheapest and most effective insulation improvements.
- Lower your thermostat by 1°C. Typically reduces heating bills by up to 10%.
- Switch to LED bulbs. LED bulbs use 80-90% less electricity than incandescent bulbs and last 15-25× longer.
Gas vs Electric: Comparing Heating Costs
At 2025 price cap rates:
- Gas: 6.4p/kWh — heating a typical 3-bed home costs approximately £50–80/month in winter.
- Electricity: 24.5p/kWh — electric heaters cost roughly 4× more per kWh than gas.
- Heat pumps (running on electricity): 2–4× more efficient per kWh than direct electric heating, making them cost-competitive with or cheaper than gas — but with high upfront cost.