Understanding how your electricity bill is calculated helps you identify high-usage appliances, compare tariffs, and reduce costs effectively.
The Basic Formula
Electricity cost = Units used (kWh) × Unit rate (p/kWh)
Plus fixed charges:
Total bill = (kWh used × unit rate) + (days × daily standing charge)
What Is a kWh?
A kilowatt-hour (kWh) is the standard unit of electricity consumption:
Energy used (kWh) = Power (kW) × Time (hours)
Examples:
- 2 kW kettle for 30 minutes: 2 × 0.5 = 1 kWh
- 60W bulb for 10 hours: 0.06 × 10 = 0.6 kWh
- 3 kW electric oven for 1 hour: 3 × 1 = 3 kWh
Typical UK Electricity Bill Calculation (2025)
At the current Ofgem price cap:
- Unit rate: approximately 24.5p/kWh
- Standing charge: approximately 61p/day
A household using 3,100 kWh/year (average):
Energy cost = 3,100 × 0.245 = £759.50
Standing charge = 365 × 0.61 = £222.65
Annual bill ≈ £982
Monthly ≈ £82
Appliance Cost Reference Table
| Appliance | Power | Usage | kWh/month | Cost/month (24.5p) |
|---|---|---|---|---|
| Electric shower (9.5kW) | 9.5 kW | 5 min/day | 24 kWh | £5.88 |
| Electric oven | 2.5 kW | 1 hr/day | 75 kWh | £18.38 |
| Fridge-freezer | 0.25 kW | Always on | 180 kWh | £44.10 |
| Washing machine | 2 kW | 4 cycles/wk | 32 kWh | £7.84 |
| TV (LED 55") | 0.09 kW | 5 hrs/day | 13.5 kWh | £3.31 |
| Phone charger | 0.005 kW | 8 hrs/day | 1.2 kWh | £0.29 |
| EV charger (7kW) | 7 kW | 1 hr/day | 210 kWh | £51.45 |
Reading Your Meter
Economy 7 meters have two readings (day and night). Night units are cheaper — ideal if you run appliances overnight.
Smart meters send readings automatically and often show real-time consumption in the in-home display.
How to Reduce Your Bill
- Switch tariff — compare deals at Uswitch, MoneySuperMarket
- Time of use — shift washing/dishwasher to off-peak hours
- Insulation — reduces heating demand
- LED bulbs — use 75% less energy than halogen
- Standby power — most devices use 1–5W on standby
- Smart thermostat — typically saves £100–£150/year