Compare appliance energy costs

Enter the power and daily use for both options. Keep the useful service comparable: two heaters should provide similar warmth, and two lighting options should provide similar light. Lower wattage is only a saving if the alternative still meets your needs.

Formula

Each option uses power in kW × operating hours × operating days. Annual saving = option A’s annual cost − option B’s annual cost. Percentage saving = annual saving ÷ option A’s cost × 100.

Worked example

Using an 800 W device for four hours daily consumes 1,168 kWh annually. A 500 W alternative on the same schedule consumes 730 kWh. The difference is 438 kWh, or 37.5% of option A’s consumption.

What the result means

A positive saving means B costs less to operate than A. A negative value means B costs more. Monthly totals average the annual schedule over 12 months.

Electricity price · United Kingdom

£0.2611/kWh is Ofgem’s average capped electricity unit rate for standard variable tariffs paid by Direct Debit in England, Scotland and Wales, valid from 1 July to 30 September 2026. It includes 5% VAT and excludes the separate standing charge. It is not an average across all contracts and does not apply to Northern Ireland. Use your own tariff where available.

Last reviewed: 9 September 2026 · Ofgem · July–September 2026

Enter the unit rate including any applicable tax. Check your bill rather than adding a tax percentage automatically. Standing charges, export payments and subscription fees are separate. Ofgem information applies to Great Britain; Northern Ireland has its own regulator and market arrangements.

Assumptions and limits

The comparison covers electricity, not purchase price, repairs, service life or differences in performance. A smaller device that needs longer to finish may not save the amount suggested by wattage alone.

Questions answered

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