Save electricity in the UK: compare running time, unit rates and standing charges

Start with the unit rate on your own bill

Find the electricity unit rate in pence per kWh and divide it by 100 before entering pounds in the calculator. Keep the daily standing charge separate: reducing an appliance's operating time does not remove that charge. Ofgem's bill guide explains this distinction for Great Britain; consumers in Northern Ireland should use their supplier's bill and Utility Regulator guidance.

The following 25p/kWh rate is an invented calculation assumption, not a current price-cap rate or a supplier offer. Use a rate including applicable VAT, without adding the tax twice. If your contract has more than one rate, calculate each period separately.

Worked example: one hour less of electric heating

Suppose a 2,000 W heater draws its full rated power for three hours a day on 90 days. Consumption is 2 × 3 × 90 = 540 kWh. At £0.25/kWh, that costs £135. Two hours a day gives 2 × 2 × 90 = 360 kWh, costing £90. The difference is 180 kWh and £45 for those 90 days.

This is a fixed-output scenario, not a prediction for a thermostat-controlled heater. If it switches on and off, measure energy over comparable days. A shorter heating period may also change comfort; do not assume that the same room temperature is maintained.

Reproduce the calculation without annualising the heating season

In the electricity calculator, choose 2 kW, three hours, seven days per week and £0.25/kWh. The average daily result is 6 kWh and £1.50. Multiply the daily result by your 90 heating days, rather than using the displayed year-round total. Repeat with two hours. Record the dates, actual operating hours and tariff beside both results.

Decide what to measure next

Compare this £45 scenario with a continuous 5 W standby load: 0.005 × 24 × 365 = 43.8 kWh, or £10.95 a year at the same assumed rate. These different time periods are explicit; neither figure is a typical household saving. Prioritise the change that fits your actual use, cost and comfort.

Check meter readings over similar periods after making a change. A lower Direct Debit payment is not proof of lower consumption: it can reflect account credit or a new payment estimate. Compare kWh first, then apply the same rate to both periods.