What size generator for home backup, camping, or jobsite?
Rule-of-thumb ranges are a starting point — your exact number comes from adding up your loads. But these brackets cover the vast majority of buyers.
Home backup: 5,000–7,500 watts
The essentials for most houses — refrigerator, freezer, well pump or sump pump, gas furnace blower, lights, phones, WiFi — land between 5,000 and 7,500 running watts. A 7,500 W portable (about 6,000 running watts) is the most popular homeowner size for a reason: it starts a 3/4 HP well pump without dimming the lights and still has room for a window AC or microwave.
Example 7,500 W load list: refrigerator (250 W) + freezer (500 W) + well pump 1/2 HP (1,000 W) + furnace blower (875 W) + LED lighting (100 W) + TV/laptops/phones (~250 W) = ~3,000 running watts, with surge headroom to spare.
What this bracket can't do: central air conditioning (~15,000 W surge without a soft-start kit), electric clothes dryers, electric water heaters, and electric ranges alongside other loads. Those need 12,000 W+ or a standby unit.
Camping & RV: 2,000–3,500 watts
For charging batteries, lights, laptops, and phones, a 2,000 W inverter is plenty — and quiet enough for campgrounds. Step up to 3,500 W if you want to run a 13,500 BTU RV air conditioner or a microwave (usually not both at once without staggering). Go inverter here: noise limits and sensitive electronics make it the obvious choice. See inverter vs. conventional.
Example 3,500 W camping list: RV AC (1,500 W running) + LED lights (100 W) + phones/laptops (~100 W) = ~1,700 running watts — comfortable, with surge covered for the AC compressor.
Jobsite: 5,000–7,500+ watts
Contractors usually buy by the heaviest tool: a 10" table saw (~1,800 W running, ~3,600 W starting) plus a compressor or charger running alongside. 5,500 W covers one heavy tool plus support loads; crews running multiple tools step up to 7,500–9,500 W. Conventional open-frame wins on jobsites — tools don't need clean power, and watts per dollar is what counts.
Example 5,500 W jobsite list: table saw (1,800 W) + cordless tool charger (300 W) + LED work lights (200 W) + phone chargers (~50 W) = ~2,350 running watts with plenty of surge margin.
When to skip portable entirely
If your must-run list includes central AC, an electric dryer, an electric water heater, or an electric range all at once, you're past portable territory. Permanently installed standby generators (20 kW and up, automatic transfer switch, plumbed fuel) are the right answer — different budget, different purchase, installed by a pro.