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 AmazonWhat size generator for a 3-bedroom house?
Short answer
To keep the essentials running in a 3-bedroom house during an outage you need a generator rated for at least 4,700 starting watts — about 3,150 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
3,150W
Peak (surge)
4,700W
Minimum generator
4,700W
Recommended
5,000W
Sizing a generator for a 3-bedroom house
Bedroom count is really a stand-in for how many people you're keeping comfortable — more rooms means more lights, more devices charging, more ceiling fans, and often a second fridge or freezer. Those per-room loads, plus a fridge and heating/cooling, are what a generator for a 3 bedrooms home has to cover in an outage. This page sizes a realistic essentials set for that.
These essentials draw about 3,150 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 4,700 watts.
To power the whole set, choose a generator rated for at least 4,700 starting watts. A 5,000W unit leaves comfortable headroom to add more — the calculator below does that math for your exact list.
Essentials wattage breakdown
| 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) ×9 | 135W | 135W |
| WiFi Router / Modem | 20W | 20W |
| Phone / Device Charger ×4 | 80W | 80W |
| LED TV (up to 55") ×2 | 300W | 300W |
| CPAP Machine | 90W | 90W |
| Ceiling Fan ×3 | 225W | 225W |
Size your own list
This page sizes a typical essentials set for a 3-bedroom house. Open the calculator with them pre-selected, then add or remove anything to match your home exactly.
Size a generator for a 3-bedroom houseRelated
Recommended midsize portable generators
Real, 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 value
Westinghouse WGen7500
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
Champion 6250W Open Frame Inverter (100519)
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 AmazonFrequently asked questions
What size generator do I need for a 3-bedroom house?
There's no single answer from square footage alone — it depends on what you run during an outage. For the essentials in a 3-bedroom house (fridge, heating/cooling, pumps, lights and device charging) you need a generator rated for at least 4,700 starting watts. We recommend a 5,000W (midsize portable) unit so you have headroom without running it at its limit.
Can a portable generator power a 3-bedroom house?
Yes, for the essentials — not for running every circuit at once. A 5,000W portable covers the outage basics this page sizes (about 3,150 running watts, peaking at 4,700W). Powering central AC, an electric range and an electric dryer simultaneously would instead call for a home standby unit spec'd by an electrician.
Why size a generator by appliances instead of square footage?
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.