Start with a room-by-room pass
Walk through each room and list appliances, built-in equipment you can reasonably model, lighting groups, chargers, and connected devices. Quantity matters: one row can represent several physically identical units only when their usage assumptions are genuinely the same.
Use room and category labels that help you review the results. The tool reports accessible tables for room, category, provenance, and largest modeled contributors; these are neutral arithmetic breakdowns, not automatic saving recommendations.
Choose the usage basis that matches your evidence
Schedule
Use electrical input watts, hours on a used day, used days per week, quantity, and duty cycle. Duty cycle represents the fraction of scheduled active time at the entered power.
Seasonal schedule
Use electrical watts, hours per active day, active days per year, duty cycle and quantity. Enter standby hours and standby days per year separately; the tool does not infer standby days from the active season.
Watts and minutes per use
Use electrical input watts, minutes for one use, weekly uses, duty cycle, and quantity. This is useful for short, repeatable sessions when a complete-use energy measurement is unavailable.
Measured kWh per use or cycle
Enter energy for one representative complete use and the weekly use count. This bypasses a separate watts, duration, and duty-cycle adjustment. Include all phases you intend the number to represent, such as preheating or drying.
Keep active and standby separate
Standby watts and standby hours are separate inputs for every basis. For scheduled loads, the production calculator prevents active and standby schedules from exceeding an average 24-hour day. A continuous operating load should be modeled as active use, not described automatically as avoidable standby.
Record provenance without inventing confidence
- Illustrative preset: an editable site-maintained scenario, not a market average.
- Product label/nameplate: a rated or declared input that may differ from cycling in service.
- Measured watts: a representative active-power measurement.
- Measured kWh: measured energy over a complete period, use, or cycle.
- User estimate: a value supplied without a measurement or product declaration.
The inventory reports the share of modeled kWh assigned measured provenance versus illustrative, label, or user-estimated provenance. It does not turn that split into a confidence score.
Use the common rate carefully
One electricity rate and currency apply to the entire inventory. Changing the common rate recalculates every item. Tiered prices, time-of-use variation, taxes, fixed fees, demand charges, credits, and other bill components are outside the single-rate cost estimate.
Measurement and safety
The U.S. Energy Information Administration distinguishes instantaneous watts from watt-hours and kWh measured over time. The U.S. Department of Energy standby-measurement guide provides context for suitable low-power measurement. Neither source validates the site's illustrative presets or makes a device safe to disconnect.
What the inventory can miss
Common omissions include central heating and cooling, electric water heating, pumps, outdoor equipment, shared building loads, electric vehicles, seasonal devices, and appliances whose cycling was observed during an unrepresentative period. A modeled total is not a meter reconciliation.
Use the optional bill-reference check to compare annualized kWh without treating the difference as waste or a diagnosis.
Open the household electricity inventory calculator
Related: accuracy guide · standby-power guide · methodology · privacy · sources
Last reviewed: August 14, 2026