About WattWorth

What you can work out

The calculators cover appliance running costs, home electric-car charging, heat pumps and gas boilers, solar panels, battery backup and whole-home electricity use. The appliance library gives starting estimates for common equipment, then lets you change the power, schedule or energy use to match your own label and routine.

Start with the calculators or browse the appliance cost library.

How a result is calculated

For something that runs at a steady power, energy is watts multiplied by hours and divided by 1,000. The result is kilowatt-hours (kWh). The running cost is that energy multiplied by the selected price per kWh. For example, a 2,000 W heater running for one hour uses 2 kWh; at €0.20 per kWh, that use costs €0.40.

Some appliances are better described by their energy label than by their rated watts. Where a source gives energy per cycle or per year, the appliance calculator starts from that figure. You can change the typical use assumptions shown on the page. Weekly schedules are annualised across 365 days, and an average month is one twelfth of that year.

Where a calculator supports off-peak use, it applies the share of use you assign to each tariff period. Emissions are estimates based on the displayed regional grid-intensity figure. They are not a measurement of the electricity used at a particular time.

Sources and assumptions

Default household energy prices and regional figures come from published sources including Eurostat, the US Energy Information Administration, Ofgem and Ember. Appliance and vehicle pages link to the sources behind their published wattage, energy-label or efficiency figures, and show the date or period supplied by each source.

A typical wattage or usage schedule is a starting assumption, not a claim about every model or household. Where a figure is our estimate rather than a published value, the page explains that distinction. For the closest answer, use your appliance label, measure its consumption, and enter the unit rate from your own bill.

Published source periods are shown with the relevant figures. Regional data is refreshed from its source feeds and checked for periods that need review; a published average can lag behind the prices currently offered by a supplier.

What the estimates do not include

These are comparisons and estimates, not quotes or a forecast of a complete bill. A result depends on the rate and usage entered. It does not account for every supplier fee, tax arrangement, appliance condition, weather effect or change in efficiency over time. Supplier tariffs and actual consumption can differ from regional averages.

Corrections and privacy

If a source or figure appears out of date, include the page address and the source or appliance label you are comparing it with. For privacy questions or requests, contact privacy@wattworth.app. See the privacy policy for details about site data.