How it works
How to calculate it
The calculator applies the values you enter to this formula:
Operating cost = AC watts ÷ 1,000 × runtime × days × electricity rate.
How to use this calculator
- Estimate average system power draw.
- Enter compressor-on runtime rather than thermostat availability.
- Apply cooling days and the local electricity rate.
Worked example
A 1,500 W unit running eight hours daily costs about $61.20 over 30 days at $0.17/kWh.
Important assumptions
- Runtime means compressor-on time, not simply thermostat-on time.
- Fan-only operation and demand charges are excluded.
- Actual use depends on climate, insulation, sizing, and thermostat settings.
Common mistakes to avoid
- Counting every thermostat-on hour as full-power runtime.
- Leaving out the indoor blower.
- Projecting one extreme day across the entire season.
Method reviewed June 10, 2026. Prices and rates are user-provided defaults and should be replaced with local values.