Cooling is one of the largest summer electricity costs in most US homes. Air conditioners cycle on and off, so the honest answer to “how much does it cost” is a range — but the maths is straightforward.
Estimate. Wattages are typical DOE/ENERGY STAR figures; cost uses the US average 18.56¢/kWh (EIA, March 2026).
Cost by AC type
| AC type | Typical watts | Cost/hour @ 18.56¢ | Cost/month (8 h/day) |
|---|---|---|---|
| Window unit (small) | ~500 W | ~9¢ | ~$22 |
| Window unit (large) | ~1,400 W | ~26¢ | ~$62 |
| Central AC (typical) | ~3,500 W | ~65¢ | ~$156 |
| Central AC (large) | ~5,000 W | ~93¢ | ~$223 |
These assume the compressor is actually running for those hours. In practice AC cycles, so a unit “on” for 8 hours might only compress for 4–6 — lowering the real cost.
See the central air conditioner and window air conditioner pages for low/typical/heavy and per-state tables.
What drives your cooling bill
- Your rate — at California’s 33.35¢ the central-AC figures roughly double versus the US average; in a cheap state they nearly halve. Check your state’s price.
- How hard it works — hotter climates, leaky homes and low thermostat settings mean more compressor time.
- Efficiency (SEER) — a higher-SEER unit or a heat pump moves more heat per kWh.
How to cut it
- Raise the setpoint a few degrees and use a programmable schedule.
- Use ceiling fans — a ceiling fan costs pennies and lets you set the AC higher.
- Seal and shade — change filters, seal leaks, close blinds on sunny windows.
Bottom line
A typical central AC costs around $150–$220 a month in peak summer at the US average rate, while a window unit cooling one room is far cheaper. Price your exact unit and rate in the calculator, and see what uses the most electricity.