How many watts does a central air conditioner use?
A central air conditioner uses 1,930–5,220 watts while running, which is 8–21.8 amps at 240 V.
Central air conditioner watts, amps and circuit
| Running watts | 1,930–5,220 W |
|---|---|
| Voltage | 240 V |
| Running amps | 8–21.8 A |
| Circuit | dedicated 240 V circuit, breaker size from the nameplate |
Also called: central ac, central air, central ac unit, home ac unit, outside ac unit, 3 ton ac.
Central air conditioner watts by size and type
| Size or type | Running watts, W | Volts, V | Amps, A | Starting watts, W |
|---|---|---|---|---|
| Central air conditioner | 1,930–5,220 | 240 | 8–21.8 | — |
| 2 ton (24,000 BTU) | 1,930–2,030 | 240 | 8–8.5 | — |
| 2.5 ton (30,000 BTU) | 2,280–2,590 | 240 | 9.5–10.8 | — |
| 3 ton (36,000 BTU) | 2,790–3,080 | 240 | 11.6–12.8 | — |
| 3.5 ton (42,000 BTU) | 3,220–3,550 | 240 | 13.4–14.8 | — |
| 4 ton (48,000 BTU) | 3,660–4,120 | 240 | 15.3–17.2 | — |
| 5 ton (60,000 BTU) | 4,690–5,220 | 240 | 19.5–21.8 | — |
What size generator runs a central air conditioner?
A central air conditioner needs a generator that supplies at least 5,220 running watts. Starting a central air conditioner takes a short surge of several times its running watts, and the surge is not listed here: size the generator from the locked-rotor amps (LRA) on the nameplate or the maker's generator guidance, not from the running watts. The generator must have a 240 V outlet or be connected through a transfer switch or interlock.
What it costs to run a central air conditioner
Running a central air conditioner at 3,575 W, the middle of its 1,930–5,220 W range, for one hour a day uses 1,304.9 kWh a year. That costs about $235 a year at $0.18 per kWh, the US average residential price for August 2026.
Your bill's total ÷ kWh used. 0.18 is the US residential average.
- Per day
- $0.64
- Per year
- $235
- Energy per day
- 3.58 kWh
- Energy per month
- 108.7 kWh
How it is calculated
- kWh per day = 3,575 W × 1 h ÷ 1,000 = 3.575
- Per month = 3.575 kWh × 30.4 days × $0.18 = $20
What affects central air conditioner power use
The running watts are the total system power, outdoor unit and indoor blower together, at 95 °F outdoors from the makers' cooling performance tables; on hotter days the draw rises. Size and efficiency rating set the running watts. The compressor surge at start is several times the running draw. The breaker comes from the maximum overcurrent protection on the unit nameplate, so it varies with the model.
How the amps are calculated
Amps = watts ÷ volts. For 5,220 W at 240 V that is 21.8 A. The 1,930–5,220 W range covers typical models; the nameplate on a central air conditioner gives the exact figure.