Use the arithmetic you can inspect
Cost equals energy in kilowatt-hours multiplied by your electricity tariff per kilowatt-hour. For example, your own measured 0.4 kWh at $0.30/kWh costs $0.12. These are illustrative inputs, not measurements of a catalog product.
For repeated use, multiply the per-session cost by sessions per week and weeks in your chosen period. Keep the tariff, duration and frequency editable. A change in household behavior can matter as much as a difference between appliances.
Rated power is an assumption, not a meter reading
A constant-power runtime estimate is rated watts divided by 1,000, multiplied by runtime hours. A user-entered 1,500 W over 20 minutes therefore gives 0.5 kWh under that assumption.
The appliance need not draw its rating continuously. Breville’s BOV900 manual describes pulsing its heating power; a rating multiplied by elapsed time is not a verified energy measurement. Include preheating and all relevant cooking batches when measuring a session.
Compare ownership cost with visible inputs
Our ownership calculation adds purchase cost, your electricity estimate and your entered maintenance/replacement costs over the chosen horizon. Do not invent an appliance lifespan or future parts expense to make a model look cheaper.
Compare the same meals and sessions when evaluating alternatives. Without comparable measured energy, report the assumption rather than a percentage energy-saving claim. The purchase price difference can be calculated independently of the unknown energy difference.
Guide authored and sources checked 2026-09-14. No hands-on testing claimed.