Best overall
Westinghouse iGen4500
4,500W start · 3,700W run
Gasoline · Inverter · 52 dBA · remote start · RV-ready TT-30R
Quiet enough for a campground and strong enough to start a 30-amp RV air conditioner.
Find on AmazonReal surge math — not just a sum
Short answer
To keep the essentials running in a 1,500 sq ft home during an outage you need a generator rated for at least 4,180 starting watts — about 2,630 running watts for a fridge, heating/cooling, pumps and lights, plus the furnace blower fan's startup surge. A 5,000W (midsize portable) unit gives comfortable headroom. Size it by the appliances you actually need, not by square footage.
Running watts
2,630W
Peak (surge)
4,180W
Minimum generator
4,180W
Recommended
5,000W
Square footage on its own doesn't tell you a generator size — a 1,500 sq ft home with gas heat and city water draws far less than the same area with an electric furnace and a well pump. What actually sets the size is the outage load: the blower fan, any pump, a window AC, the fridge and your lights. This page sizes a realistic essentials set for a home this size.
These essentials draw about 2,630 running wattstogether. You don't add every appliance's starting watts, though — only one motor surges at a time, so the generator only has to cover that running total plus the single largest startup surge (the furnace blower fan's), which brings the peak to 4,180 watts.
To power the whole set, choose a generator rated for at least 4,180 starting watts. A 5,000W unit leaves comfortable headroom to add more — the calculator below does that math for your exact list.
| Appliance | Running watts | Starting watts |
|---|---|---|
| Refrigerator / Freezer | 700W | 2,200W |
| Furnace Blower Fan (1/2 HP) | 800W | 2,350W |
| Sump Pump (1/3 HP) | 800W | 1,300W |
| LED Light Bulb (each) ×8 | 120W | 120W |
| WiFi Router / Modem | 20W | 20W |
| Phone / Device Charger ×2 | 40W | 40W |
| LED TV (up to 55") | 150W | 150W |
This page sizes a typical essentials set for a 1,500 sq ft home. Open the calculator with them pre-selected, then add or remove anything to match your home exactly.
Size a generator for a 1,500 sq ft homeReal, widely available units in the 3,500 – 8,500W class. Independent picks — we're not affiliated with any manufacturer or retailer and earn nothing from these links.
Best overall
4,500W start · 3,700W run
Gasoline · Inverter · 52 dBA · remote start · RV-ready TT-30R
Quiet enough for a campground and strong enough to start a 30-amp RV air conditioner.
Find on AmazonBest value
9,500W start · 7,500W run
Gasoline · Remote start · transfer-switch ready (L14-30R)
Serious home-backup wattage — enough for essentials circuits via a transfer switch — at a midsize price.
Find on AmazonQuietest
6,250W start · 5,000W run
Gasoline · Open-frame inverter · 69 dBA · <3% THD
50% quieter and 20% lighter than a conventional 5,000W unit, with inverter-clean output.
Find on AmazonThere's no single answer from square footage alone — it depends on what you run during an outage. For the essentials in a 1,500 sq ft home (fridge, heating/cooling, pumps, lights and device charging) you need a generator rated for at least 4,180 starting watts. We recommend a 5,000W (midsize portable) unit so you have headroom without running it at its limit.
Yes, for the essentials — not for running every circuit at once. A 5,000W portable covers the outage basics this page sizes (about 2,630 running watts, peaking at 4,180W). Powering central AC, an electric range and an electric dryer simultaneously would instead call for a home standby unit spec'd by an electrician.
Because two homes of the same size can have completely different electrical loads — gas vs. electric heat, well pump vs. city water, central vs. window AC. Square footage is only a rough proxy; the honest number comes from adding up the specific appliances you need, which is exactly what this page and the calculator do.