Free browser tool
Appliance energy cost calculator
List your devices with their power in watts and how many hours a day you use them, add your price per kWh, and see the cost and kWh per device, each device's share and the total. Compare scenarios or time-of-use prices in the Advanced JSON.
Runs on this device. No upload, account or tracking.
Your devices and price
Three capital letters such as EUR, USD or GBP. Nothing is converted.
From your bill or contract. Fixed fees and taxes are not added unless included here.
Up to 8,784 hours (a leap year). Device hours are then per period.
Recorded in the report; no rating is looked up.
Devices
Power in watts while on, and hours of use per day. Standby power, if given, counts for the rest of the time. Blank rows are ignored.
Advanced: scenarios, time-of-use prices and shares as JSON
Edit to calculate from this JSON instead of the form: several "scenarios" to compare, "tariffs" with start_hour, end_hour and rate_per_kwh covering the period, device "windows" in elapsed hours (active, or standby with its own power), kW ratings, a "reference_power" and "allocations" that split a scenario between people. Editing the form again rewrites the first scenario and keeps the others.
Up to 24 scenarios, 100 devices and 100 tariff windows per scenario, 100 windows per device and 1,000 device windows in all; periods up to 8,784 hours; values up to 1,000,000,000,000 with at most nine decimal places; up to 100 KB of input. Prices, ratings and hours are your assumptions: no live tariffs, fixed fees or taxes are added.
Result
Result
Technical output
The download contains the same JSON: exact decimal kWh and cost per device, window and scenario, and your inputs.
About this tool
What this tool does
Work out the energy use and running cost of your appliances per day, month or year from their power in watts, the hours you use them, any standby power and the price per kWh you pay, in your browser.
Limits and safe use
Up to 24 scenarios, 100 devices and 100 tariff windows per scenario, 100 windows per device and 1,000 device windows in all; periods up to 8,784 hours; values up to 1,000,000,000,000 with at most nine decimal places; up to 100 KB of input. Prices, ratings and hours are your assumptions: no live tariffs, fixed fees or taxes are added. Use your own bill's price and your devices' real power. The result is an estimate from your numbers, not a measurement, a live tariff or a savings recommendation, and nothing is sent to a server or a model.