Will a 12,000W generator run two AC units?
Running central ac (3-ton), window ac (12k btu), refrigerator, household lights (led) on a 12,000W generator: the steady draw is 5,160W, but it peaks at 14,260W when the central ac (3-ton) starts.
| Load | Running | Starting |
|---|---|---|
| Central AC (3-ton) | 3500W | 12600W |
| Window AC (12k BTU) | 1300W | 3380W |
| Refrigerator | 160W | 480W |
| Household lights (LED) | 200W | 200W |
Why the peak is what matters
A generator doesn't stall on the running total — it stalls on the surge. The single largest startup spike here comes from the central ac (3-ton). Add it to the running load of everything else and you get a 14,260W peak. Since that exceeds 12,000W, the generator would overload the instant that motor starts.
A soft-start kit on the central ac (3-ton) could cut its surge ~65% and may bring this within reach of a smaller generator.
Size your exact setup
This covers a typical load set. Your actual appliances will differ — size your real situation in the calculator:
Common questions
Will a 12,000W generator run two AC units?
Not reliably. Running central ac (3-ton), window ac (12k btu), refrigerator, household lights (led) draws 5,160W continuously, but peaks at 14,260W when the central ac (3-ton) starts. A 12,000W generator falls short of the 14,260W surge — you'd want about 17,500W.
What's the difference between running and starting watts?
Running watts is the steady draw; starting (surge) watts is the brief spike when a motor starts. Generators must handle the surge, not just the running total — that's why this calculation matters.