Household electricity planner
Add appliances, model seasonal use and see their combined annual electricity cost and largest contributors.
Starting rows are hypothetical examples, not measured averages. This is the total of the appliances you enter, not a complete household bill. Avoid counting the same energy twice.
Reference: Ofgem GB average Direct Debit rate, 1 October–31 December 2026: 26.32p/kWh. Checked 8 November 2026. Use your own bill; regional and payment-method rates differ, and Northern Ireland has a separate market. Annual costs hold the entered rate constant; they are not a forecast. Standing charges are excluded. For time-of-use tariffs, calculate each rate's consumption separately and add the costs.
Add up to 20 appliances or non-overlapping groups. For a group, enter its combined energy, not the energy of just one device.
Save downloads a plain-text JSON file containing your appliances, usage and tariff. Load reads a selected file on your device; it is not uploaded. Keep the file to reuse or move your plan between devices. Files must be valid Home Cost Wise plans up to 50KB. Manage downloaded files in your own folders. Privacy details · How to measure your own figures.
Worked example: Adding two independent loads
These fixed teaching inputs are separate from the editable calculator above and are not current tariff or product claims.
- Inputs
- A fridge-freezer label of 220kWh/year and a separate hypothetical 10W light used five hours every day.
- The working
- Light: 10 ÷ 1,000 × 5 × 365 = 18.25kWh/year. Combined: 220 + 18.25 = 238.25kWh/year.
- The result
- £59.56 a year for those two entered loads. This excludes every unlisted device and standing charge. Do not add standby already included in an annual label or complete measurement.
How this calculator works
Each row is converted to annual kWh using its chosen energy unit. Non-annual rows use active weeks and uses per active week. Add the row costs at the shared tariff. Annual-label rows are already annual; avoid overlapping measurements.
Cost in pounds = energy in kWh × electricity rate in pence ÷ 100. Monthly costs are annual costs divided by 12; daily costs are divided by 365. These are averages over a year. Calculations retain precision until display rounding.
Get a more useful estimate
Read our step-by-step guide to measuring appliance electricity before treating a nameplate rating as a measured average.
Start with the rate on your bill and energy information for your exact model. A plug-in energy monitor can help measure suitable plug-in appliances; follow its safety instructions and power limits. Do not apply full-power wattage for 24 hours to a cycling fridge or freezer.
What is excluded?
The day/night comparison includes the standing charges you enter; appliance-only tools exclude them. Gas, water, detergent, maintenance, discounts and purchase costs are excluded unless the tool explicitly asks for a purchase premium. Usage and tariffs can change. The reference tariff covers Great Britain and does not represent Northern Ireland or every contract.
Read our sources and assumptions →Common questions
Is this my complete electricity bill?
Only the appliances and usage you enter are included. Standing charges, unlisted devices and other fuel costs are excluded. Compare your total kWh with a bill covering the same period to identify gaps, without treating the difference as proof of wasted energy.
Can I save the plan as a file without an account?
Yes. Save plan to file downloads a plain-text JSON file with your appliance rows and tariff. Load plan from file reads a file you select on your device and validates it before applying it. Files are not uploaded or synced to an account. Keep the file to reuse your plan on another device.