Select the appliances you need to run during an outage. We'll calculate your load, recommend a kW range, and show matching models — including noise and permit implications.
Click each appliance you need to run during an outage. Startup (surge) watts are factored automatically.
Generator size is measured in kilowatts (kW) of output power. Sizing involves two calculations: running watts (the continuous load of everything running simultaneously) and starting watts (the surge current when motors — AC, refrigerator, well pump — start up).
The generator must handle both. A common mistake: sizing only for running watts and getting a generator that trips its overload breaker every time the AC compressor starts.
| Appliance | Running Watts | Starting Surge | Notes |
|---|---|---|---|
| Central AC (3 ton) | 3,500 W | 8,000–9,000 W | Largest surge item in most homes |
| Central AC (5 ton) | 5,500 W | 13,000 W | Requires 20+ kW generator |
| Well pump (1 HP) | 750 W | 2,000–2,500 W | Common surge issue on smaller generators |
| Electric water heater | 4,000 W | No surge | High running draw; consider load shedding |
| Electric dryer | 5,500 W | No surge | Often excluded from generator circuits |
| Refrigerator | 150–200 W | 800–1,200 W | Low running, moderate surge |
| Gas furnace (blower only) | 600–800 W | 1,200 W | Gas furnace still needs electricity for blower |
| Sump pump (1/2 HP) | 800 W | 1,300–2,000 W | Critical in flood-prone areas |
| Microwave | 1,000–1,500 W | No surge | High running wattage while in use |
| EV charger (Level 2) | 7,200 W | No surge | Often excluded from generator circuits |