How many watts does a central air conditioner use
While it runs, a central air conditioner draws 3,000 to 3,500 W, and startup takes 5,000 to 6,000 W for one second. A portable rated 5,000 W is the smallest one that can run it.
3,500 Wrunning, top of range
6,000 Wstarting surge
5,000 Wsmallest generator that runs it
Watts for running and starting
| Load | Running | Starting |
|---|---|---|
| Central AC, 3 ton | 3,000 to 3,500 W | 5,000 to 6,000 W |
| Central AC, 2 ton | 2,000 to 2,500 W | 3,500 to 4,500 W |
| Central AC, 4 ton | 4,000 to 5,000 W | 6,500 to 8,000 W |
Source: Champion's wattage chart, 04-17-26. Find the exact wattage, or the amps, on the nameplate of your central air conditioner. Multiply the amps by 120 V. Use 240 V only with a two-pole breaker load, such as a well pump.
Smallest generator able to start it
A generator must handle 3,500 W, no more than 80% of what it's rated for, and give 6,000 W at startup. The smallest common portable that manages both is 5,000 W. Other loads add their running watts to the same generator.