Air Conditioning calculator
AC Running Cost Calculator
Estimate monthly air conditioner running cost using watts, hours, duty cycle, days, and electricity rate.
When to use this calculator
Use this calculator when you know or can estimate the air conditioner's power draw and want a monthly cooling cost. It is different from BTU sizing because cost depends on watts and runtime.
The duty cycle is important because many AC units do not run the compressor at full power every minute. Room heat load, insulation, thermostat setting, filter condition, and climate change the active running time.
Formula used
AC kWh = watts ÷ 1,000 × hours × days × duty cycle. Cost = kWh × electricity rate.
The formula is intentionally simple so it can be used for quick planning. Real bills, quotes, and installation costs can include fixed fees, taxes, tiers, labor, product limits, and site-specific conditions that a calculator cannot see.
Input guide
| Input | How to use it |
|---|---|
| Watts | Use rated or measured power draw. |
| Hours per day | The time the AC is on, not always the compressor-on time. |
| Duty cycle | Estimated percentage of active compressor operation. |
| Rate and days | Use your local kWh price and billing period. |
Examples
Summer estimate
A 1,200 W AC used 8 hours daily for 30 days at 60% duty uses 172.8 kWh.
Thermostat effect
Raising the thermostat slightly can reduce duty cycle in many rooms, especially with shade and clean filters.
How to get a more accurate result
- Measure power where possible because inverter units vary widely.
- Run hot-day and mild-day scenarios.
- Clean filters and seal air leaks before judging the unit.
Common mistakes to avoid
- Using BTU as if it were watts.
- Assuming 100% duty cycle all month for every AC.
- Ignoring insulation, sunlight, and thermostat behavior.
Quick checklist before relying on the result
- Find AC wattage.
- Estimate hours and duty cycle.
- Use real kWh rate.
- Compare mild and peak summer cases.
FAQ
What is duty cycle?
It is the share of time the compressor is actively working during the AC-on period.
Is inverter AC different?
Yes. Inverter units can vary power instead of simply cycling on and off.
Can this size my AC?
No. Use the BTU calculator for sizing and this calculator for running cost.