1,200 sq ft generator sizing scenarios
A smaller home often fits a mid-size standby unit when the largest loads are a single A/C, refrigerator and gas-furnace blower. The table below is not a substitute for a load calculation; it shows how backup goals can change the likely equipment class even when the house size stays the same.
| Backup goal | Planning class | Typical approach |
|---|---|---|
| Essentials only | 10–14 kW | Refrigeration, lighting, outlets, gas-furnace blower and a selected pump. |
| Comfort-focused | 14–18 kW | Adds modest central A/C or another medium load when startup is manageable. |
| Broader whole-home | 18–22 kW | More overlap between A/C and 240-volt appliances; verify carefully. |
The loads that matter most
Square footage mostly hints at how many circuits and comfort systems a home might contain. Generator sizing is driven by power demand. Central A/C compressors, heat pumps, well pumps and other motors create a temporary startup surge. Electric water heaters, ranges, dryers, EV chargers and resistance heat are large continuous loads.
- HVAC: compressor startup can be the single biggest peak event.
- Heating: gas-furnace blowers are modest compared with electric heat strips.
- Water: well pumps add motor surge; electric water heaters add a large steady load.
- Lifestyle loads: pools, spas and EV charging can be shed during an outage to keep the generator smaller.
A smarter way to size the system
- List the circuits and appliances you truly need during an outage.
- Use equipment nameplate watts or volts/amps when available.
- Add normal running loads.
- Add the largest extra starting demand from a motor-driven load.
- Leave headroom and round up to a common generator class.
- Ask the installer whether load management can reduce simultaneous demand.
Calculate generator size for my home →
Cost matters too
A larger generator can increase equipment cost and may require different electrical, fuel and site work. Once you have a likely size class, use our installation-cost calculator to estimate a national planning range before requesting local bids.
Frequently asked questions
Is 12–18 kW enough for every 1,200 sq ft house?
No. It is a planning range, not a guarantee. A 1,200-square-foot all-electric home can need much more capacity than a gas-heated home of the same size.
Should I size by square footage alone?
No. Use square footage only as context. Actual electrical loads and motor-starting demand are more important.
Can load management reduce the generator size?
Often, yes. Approved load-management controls can keep discretionary high-wattage loads from operating while the generator is already heavily loaded.