What Size Generator for a 1,200 Sq Ft House?

Understanding the Power Requirements

A 1,200 sq ft house is typically a starter home, older ranch, or small cottage — often with a gas furnace, single-zone AC, and a moderate appliance load. Sizing a generator for this home is straightforward: the essential circuits draw 3,500–4,500W running, with the sump pump or well pump providing the peak surge. A quality 5,500–6,500W generator handles everything comfortably with headroom for a window AC unit.

Typical 1,200 sq ft home load: refrigerator (150W), sump pump 1/2 HP (800W), furnace blower (600W), LED lighting (100W), TV and devices (350W), and a microwave (1,200W running in use). Total running load: approximately 3,200W sustained. The sump pump surge (2,400W) is the peak. With a safety margin, a 5,000W generator handles the essentials; 6,500W adds comfortable headroom for a window AC.

Choosing the Right Generator Size

Best generator options for a 1,200 sq ft house: The Champion 100554 9,000W or Westinghouse WGen7500 provide substantial headroom. For a right-sized option, the Generac GP5500 (5,500W rated, 6,875W surge) is the ideal match — enough power for all critical circuits without the extra weight and fuel cost of a larger unit. For portable inverter power, the Champion 3500W dual-fuel handles essentials only.