About & methodology

WattCost answers one question well: what an appliance costs to run where you live, and whether a more efficient one is worth buying. Every figure can be traced to a source and recomputed with your own numbers.

How running costs are calculated

Cost = watts ÷ 1,000 × hours of use × price per kWh. Each appliance has a low, typical and high wattage taken from manufacturer specifications and published measurements, and typical hours of use that you can change on every page.

• Seasonal appliances such as heaters, air conditioners, fans and pool pumps are counted only for the days of their season, which the page states and lets you change. Per month means a month of use.
• Appliances that do a fixed job, such as kettles, chargers and water heaters, use the same energy whatever their power: a stronger one finishes sooner. Their tables keep the daily cost the same on every row.
• Standby is listed separately where an appliance draws power when off.

Where the prices come from

Average residential prices from each country's statistics office or regulator: the US Energy Information Administration for the national and state averages, Ofgem's price cap for the UK, BDEW for Germany, the regulated EDF Tarif Bleu for France, the Australian Energy Regulator, and Hydro-Québec's annual comparison for Canadian provinces. The price table lists every rate with its source and date. Prices are reviewed when the source publishes: monthly for the US, quarterly for the UK price cap.

Household benchmarks

The household pages start from the consumption figure each regulator publishes for a household type and split it with official end-use shares. Nothing there is an assumption dressed up as data: where a figure is derived rather than published, the page says how.

• United States: EIA Residential Energy Consumption Survey 2020, Table CE2.1, average kWh per household using electricity (2020).
• United Kingdom: Ofgem Typical Domestic Consumption Values, decision May 2026, effective 1 July 2026 (2026-07).
• Germany: Stromspiegel für Deutschland (co2online, with the Federal Ministry for the Environment), average consumption by persons and building type (2024).
• France: Enedis, Bilan électrique 2024: consommation moyenne annuelle par site résidentiel (2024).
• Australia: Australian Energy Regulator, Residential energy consumption benchmarks (Frontier Economics, December 2020), temperate climate zone (Sydney), households without a swimming pool (2020-12).
• Canada: Natural Resources Canada, Survey of Household Energy Use 2019, Table 3.5a electricity intensity per household (GJ converted at 277.78 kWh/GJ) (2019).

Efficiency upgrades

The upgrade pages compare a common inefficient model with a current efficient one using energy label thresholds, ENERGY STAR guidance and the US Department of Energy's test assumptions, and state the usage behind every figure. Paybacks are computed from those figures at local prices, for two cases: replacing a working appliance now, and choosing the efficient model when you are replacing anyway.

Limits

These are estimates for typical models and typical use. Your appliance's label and the unit rate on your bill will always be more accurate, and you can enter both on every page. Prices exclude standing charges.

Found a wrong figure or a missing appliance? See the contact page. Read our privacy policy.

Last reviewed Oct 2026.