Calculators · Cost to run
How much does it cost to run an air conditioner?
A central air conditioner is usually the biggest single line on a summer electric bill — roughly 26 kWh on a hot day for a typical 3-ton system. Because it cycles on and off with the thermostat, the honest way to price it is from real daily energy, not nameplate watts. What it costs you comes down to your rate.
per day
$3.24
per month
$98.62
per year
$1182.55
A central air conditioner uses about 26 kWh a day, costing roughly $3.24/day or $98.62/month at 12.46¢/kWh.
Runs entirely in your browser — nothing you type is sent anywhere. Estimates only; your actual bill depends on your usage and includes delivery charges on top of the supply rate.
What it costs per hot day, at real rates
Based on a 3-ton system running through a hot day (~26 kWh), priced at three of the utilities we track:
| Utility | Rate | Cost per hot day |
|---|---|---|
| PECO (PA) | 10.789¢/kWh | $2.81 |
| BGE (MD) | 14.609¢/kWh | $3.80 |
| ComEd (IL) | 10.399¢/kWh | $2.70 |
Supply rate only; delivery charges are extra. Use the calculator above for your own utility and usage.
Central AC energy by system size (hot-day estimate)
| System size | Cools about | Running watts | Hot-day energy |
|---|---|---|---|
| 2 ton (24,000 BTU) | ~1,000 sq ft | ~2,400 W | ~18 kWh |
| 3 ton (36,000 BTU) | ~1,500 sq ft | ~3,500 W | ~26 kWh |
| 4 ton (48,000 BTU) | ~2,000 sq ft | ~4,800 W | ~34 kWh |
| 5 ton (60,000 BTU) | ~2,500 sq ft | ~6,000 W | ~42 kWh |
Cycles on and off, so daily energy depends on climate, runtime, and the unit's SEER rating.
How to cut the cost
- 1
Raise the setpoint a few degrees
Every degree higher in summer cuts cooling energy roughly 3%. Setting 78°F instead of 72°F can shave 15–18% off the AC's share of the bill.
- 2
Let it drift when you're out
A programmable or smart thermostat that eases off while you're away or asleep beats cooling an empty house all day.
- 3
Change the filter, clear the coils
A clogged filter or dirty outdoor coil makes the unit run longer for the same cooling — more kWh for nothing.
- 4
Add fans and close blinds
A ceiling fan (~60 W) lets you raise the thermostat a few degrees in comfort, and closed blinds on the sunny side cut the heat the AC has to remove.
Common questions
- How much does it cost to run an air conditioner per hour?
- A 3-ton central AC draws about 3,500 watts while running, so roughly 3.5 kWh per hour of actual run time — about 45¢/hour at 13¢/kWh. But it cycles, so it isn't running the full hour; daily energy is the more honest measure.
- Is central AC or a window unit cheaper to run?
- Per unit of cooling, a window AC costs less to run because it cools one room, not the whole house — but it also cools far less. If you only need one or two rooms cool, window units usually win; for a whole home, central is more efficient per square foot.
- Why did my summer electric bill jump so much?
- Air conditioning is about 19% of the average home's annual electricity (EIA), concentrated into a few hot months — so summer spikes. In 2025–26 a higher per-kWh rate (the PJM capacity increase) stacks on top, which is why bills feel worse than the heat alone explains.
- Is it cheaper to leave the AC on all day or turn it off?
- For most homes, letting it drift warmer while you're out and cooling back down beats running it flat-out all day. A smart thermostat automates this without leaving you in a hot house at 5 p.m.
Hiring out the wiring?
Before you pay anyone to touch your panel or wiring, make sure they're actually licensed. You can check a contractor's license on StateCreds — our sister site.
Verify a contractor's license by state →If the summer bill jumped more than usage explains, your rate may have risen too.