All worked examples below use explicitly chosen inputs. They are not measured household averages, utility quotes, or guaranteed savings.
Compare the same schedule with explicit assumptions
The example fan draws 50 W throughout its eight hours. The example AC draws 1,000 W while active for 60% of an eight-hour schedule. That is 4.8 equivalent full-power hours, not eight. Neither wattage is a claim about your equipment.
| Scenario | Daily energy | Monthly cost |
|---|---|---|
| 50 W fan, 8 hours | 0.4 kWh | $2.40 |
| 1,000 W AC, 8 scheduled hours, 60% active | 4.8 kWh | $28.80 |
| Both scenarios together | 5.2 kWh | $31.20 |
Use electrical input power
A cooling-capacity figure in BTU/h cannot be used as watts. Read electrical input specifications or use suitable measurements. Fan speed, AC operating conditions, and inverter control can change power during a session.
If a measured AC average is 600 W over eight hours, enter 600 W and eight hours at 100% active time. Reducing that average by another 60% would undercount use.
Reference: Virginia Cooperative Extension: estimating appliance energy use
A dollar difference is not a comfort equivalence
The $26.40 difference between these examples is only a modeled electricity difference. It does not establish that a fan can replace the AC for the same room and conditions.
If using a fan changes your AC schedule, compare the combined new fan-plus-AC energy with the old AC schedule. Adding a fan while keeping every AC input unchanged adds the fan’s electricity to the total.
Budget for the cooling season
A monthly pattern repeated 12 times is not a seasonal forecast. Four months of the example AC pattern cost $115.20, while a twelve-month repetition costs $345.60. Use realistic months and separate unusually hot periods if you have better readings.
Sources & calculation notes
References checked 2026-10-09. Example arithmetic is calculated by HomeWattCheck. Article review dates are separate from the EIA data period displayed in our calculators.
Each calculator states its scope beside the result. Appliance tools estimate electricity at one rate; the time-of-use comparator includes two price periods and entered fixed fees. Complex tariffs may need additional calculations. State averages describe reported residential revenue per kWh, not your utility’s offer. See our data sources and methodology or state rate comparison.