Describe the season you want to model
List the months when you expect to need cooling and the rooms involved. A short shoulder-season schedule and a hot-month schedule do not need to share the same inputs. If you use two appliances, give each its own line before combining costs.
Start with a realistic range rather than a prediction about future weather. The EIA explains that electricity prices and demand can vary; your calculation should state the tariff it assumes. Update that input if your own plan changes, rather than treating a previously used example rate as fixed.
Add three illustrative months
The table describes one hypothetical appliance at $0.18/kWh. The power values are average-draw scenarios, not measured performance or regional weather averages.
| Scenario | Average draw and schedule | Energy | Cost |
|---|---|---|---|
| Light-use month | 300 W × 4 h × 30 days | 36 kWh | $6.48 |
| Middle month | 600 W × 8 h × 30 days | 144 kWh | $25.92 |
| Heavy-use month | 800 W × 10 h × 31 days | 248 kWh | $44.64 |
Total modeled energy is 428 kWh, costing $77.04. Repeating the middle month three times would instead give $77.76. The closeness here is coincidental; different schedules can produce much larger differences.
Avoid counting cycling twice
An average draw calculated from an entire observation period already includes changes in power during that period. If you use that figure, do not apply another arbitrary compressor-on percentage.
Likewise, distinguish hours when the unit is available from a separately measured average over a full day. Keep the power average and elapsed time on the same basis. The measurement guide shows how to preserve that connection in a log.
Update the remaining months as evidence arrives
At the end of each month, retain the original scenario and add the measured or billed evidence beside it. Separate the appliance estimate from whole-home energy; other equipment can explain part of a bill change.
Revise the remaining budget when actual use provides a better basis, without pretending that the new estimate is guaranteed. The calculator’s annual result repeats a chosen month, so calculate varied months individually and add them outside the tool. A useful seasonal budget shows what is known, what is assumed and where the largest uncertainty remains.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.