What size generator to run a central ac (3-ton)?
Central AC (3-ton) sizing at a glance: it draws 3500 running watts, surging to 12600W at startup.
| Spec | Value |
|---|---|
| Running watts | 3500W |
| Starting (surge) watts | 12600W |
| Recommended class (this load + margin) | 15500W |
Why the startup surge matters
Because a central ac (3-ton) has a motor, it surges to about 12600W at startup — roughly 3.6× its running draw. If you size a generator only for the running watts, it can stall the instant the central ac (3-ton) switches on. Always size for the surge.
Sizing the whole system
The number above covers the central ac (3-ton) on its own with a safety margin. In a real outage you'll run other things too — and the right method is your total running load plus the single largest surge among everything, not the sum of every surge. Use the full calculator to size your actual setup:
Common questions
How many watts does a central ac (3-ton) use?
A typical central ac (3-ton) draws about 3500 running watts, but needs roughly 12600 watts at startup due to motor surge.
What size generator runs a central ac (3-ton)?
For the central ac (3-ton) alone plus a safety margin, a 15500W (≈15.5kW) class generator is appropriate. Add your other essential loads to size the full system.