❄️How much does it cost to run an air conditioner?
A air conditioner draws about 500 to 1,440 watts (a 5,000–12,000 BTU window unit). Running 8 hours a day and the US-average 17¢/kWh, that’s about $20–$59 a month ($248–$715 a year) — roughly $0.085–$0.24 an hour while it’s on.
These are estimates, not a meter reading. The wattage and energy figures are typical US ranges and the 17¢/kWh is the national-average rate — the math is exact once you plug in your own wattage and rate. Your real cost depends on the specific unit, your settings and your utility.
Energy and cost, broken down
| Timeframe | Energy (kWh) | Cost @ 17¢/kWh |
|---|---|---|
| Per hour running | 0.50–1.4 | $0.085–$0.24 |
| Per day (8 h) | 4.0–11.5 | $0.68–$1.96 |
| Per month | 120–346 | $20–$59 |
| Per year | 1460–4205 | $248–$715 |
At the US-average 17¢/kWh. On a cheap rate (~11¢) these drop about a third; in California, New England or Hawaii (~33¢+) they roughly double. Ranges reflect the typical span of unit sizes and settings.
Why it costs what it does
Cooling cost tracks the unit's size in BTUs, which sets its wattage. A small 5,000 BTU window unit draws about 400–500 watts; a big 12,000 BTU one runs 1,100–1,440 watts. Portable units use a bit more for the same cooling. Central air is a different scale entirely — the compressor plus air handler pulls 3,000–5,000 watts, so central runs roughly $0.50–$0.85 an hour while the compressor is on. The thermostat setting and how well the room is sealed matter as much as the sticker BTU.
How to run it for less
- Set the thermostat as high as is comfortable — every degree cooler raises runtime; 78°F when home is the common efficiency target.
- Match the unit to the room: an oversized AC short-cycles and dehumidifies poorly, an undersized one runs flat-out. Roughly 20 BTU per square foot.
- Run a ceiling fan with the AC so you feel cooler at a higher thermostat setting — the fan costs pennies an hour next to the compressor.
- Seal the window kit and close blinds on the sunny side; a leaky install or afternoon sun makes the compressor run far longer.
Keep going
Frequently asked
How much does it cost to run a window AC for 8 hours?▾
About $0.70 to $2.00 for an 8-hour stretch on a window unit — a small 5,000 BTU model at the low end, a 12,000 BTU one at the top, at the US-average 17¢/kWh. Note the compressor cycles off once the room hits temperature, so a well-sealed room bills less than the flat-out figure. Central air is far more: $4–$7 for the same 8 hours.
Is a window unit or central air cheaper to run?▾
Per hour, a window unit is much cheaper because it cools one room on 500–1,440 watts, while central air runs the whole house on 3,000–5,000 watts. If you only need to cool the room you're in, a window or portable unit costs a fraction of running central air. Central makes sense when you need the whole home cool; cooling one occupied room with a window unit is the cheapest approach for a single person.
How do I work out what a air conditioner costs to run for my electricity rate?▾
Take the wattage ÷ 1,000 to get kilowatts, multiply by the hours you run it, then by your electricity rate. Find your rate on your bill (total ÷ kWh used) — the US average is about 17¢/kWh, but it ranges from ~11¢ in the cheapest states to 30–42¢ in California, New England and Hawaii. So the same air conditioner costs roughly 35% less on a cheap rate and nearly double on an expensive one than the figures here.
What is the average price of electricity in the US?▾
About 17¢ per kWh for residential customers as a national average (2026). The cheapest states — parts of the Midwest and Pacific Northwest — sit near 11¢, while California, most of New England and Hawaii run 30¢ to over 40¢. Your exact rate is on your utility bill; divide the dollar total by the kWh used, or read the per-kWh charge directly.