The short answer

For separate operating modes, sum average watts multiplied by non-overlapping hours and divide by 1,000 to get daily kWh. Total daily hours must not exceed 24. Unassigned hours remain excluded, and measured whole-day energy must not be combined with mode estimates covering the same period.

Use the electricity cost calculator
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One appliance can have several electrical states

Active work, idle time, sleep and standby can draw different power. Treat each as a separate time interval, with an average suited to that mode. A computer power-supply rating, for example, is not a measurement of every desktop task; a coffee machine’s heater may cycle during keep-warm operation.

Open the electricity calculator and choose separate active, idle and standby modes. The same editor supports blanket and air-purifier routines, with up to six modes and a source or assumption for every row.

Check the arithmetic with an explicit routine

Consider these invented inputs for demonstrating the method:

Mode Average watts Hours/day Energy/day
Active 100 4 0.4 kWh
Idle 20 2 0.04 kWh
Standby 0.5 18 0.009 kWh

The total is 24 hours and 0.449 kWh/day. At $0.20/kWh for 365 use days, cost is $32.777, displayed as $32.78. None of these values is a preset claim about a real TV, computer or coffee machine.

Do not overlap daily periods

A routine of four active hours plus 24 standby hours is impossible for the same appliance on the same day. The editor rejects mode hours above 24. When hours total less than 24, it reports the remaining time as excluded rather than assuming zero consumption.

A connected appliance may still draw power in those unassigned hours. Add a documented off/standby state or measure a complete day if you want a complete-day estimate. Multiple appliances following different schedules need separate calculations or planner rows.

Average power needs an observation boundary

For an intermittent mode, a momentary reading may miss heating, fan changes or network activity. Accumulated kWh divided by elapsed hours gives an average for that observed interval: average watts = kWh × 1,000 ÷ hours.

For example, 0.06 kWh over three hours corresponds to 20 W on average. Record what happened during those hours. Do not label it a permanent product characteristic when operating conditions can change.

Choose modes or complete measured use

If a whole-day sample already includes active and idle operation, price that sample directly. Adding standby rows for the same day counts some energy twice. Conversely, a measurement of only an active task leaves the rest of the day outside its boundary.

Use the standby audit when listing selected modes across several devices. Use the shared mode editor when describing several states of one appliance. The distinction keeps the time boundary clear without forcing a household into one universal schedule.

Save enough context to repeat the comparison

Keep the model, mode names, average draw source, daily hours and chosen use days. Shared reports retain those fields. A reduction in estimated energy is conditional on the entered schedule actually changing; it does not show every state can be safely or practically removed.

For repeat measurements, the journal comparison uses weighted observations and requires comparable tasks. Cost scenarios apply a common tariff separately from the observation itself.