Plan backup power before the lights go out
Sourced appliance wattages and simple calculators for generator size, power-station runtime and UPS runtime. Every number shows where it came from, and every assumption is labeled.
Size a generatorBrowse the wattage chartCalculators
Generator size calculator
Add up running watts plus the biggest motor start to find the generator rating you need.
Open calculator →Power station runtime
Turn battery watt-hours and your loads into hours (or days) of runtime, with output-limit checks.
Open calculator →UPS runtime
Estimate how long a UPS or battery bank keeps your router, PC or home lab running.
Open calculator →Appliance wattage chart (preview)
49 appliances with running and starting watts and a source link on every row. See the full chart.
| Appliance | Running W | Starting W | Source |
|---|---|---|---|
| Refrigerator or freezer (ENERGY STAR) | 132–192 | 1,200 | Honda Power Equipment |
| Microwave oven, 1,000 W | 1,500 | 1,500 | Honda Power Equipment |
| Window AC, 10,000 BTU | 1,500 | 2,200 | Honda Power Equipment |
| Central AC, 3-ton | 3,000–3,500 | 5,000–6,000 | Champion Power Equipment |
| Furnace fan (gas/oil), 1/3 hp | 700 | 1,400 | Honda Power Equipment |
| Sump pump, 1/2 hp | 1,050 | 2,150 | Honda Power Equipment |
| Internet router / modem | 10–20 | — | Champion Power Equipment |
| CPAP machine (no heated humidifier) | 30–60 | — | Champion Power Equipment |
Guides
How many watts does a refrigerator use?
Running, starting and average watts — and how long food stays safe.
Read guide →Generator vs portable power station
Watts vs watt-hours, safety, and which one fits which outage.
Read guide →Alabama power outage checklist
How to report an outage, food and CO safety, and storm-season prep.
Read guide →How we handle numbers. Wattages come from published manufacturer charts (Honda, Champion) and are marked “approximate.” Home-lab figures from third-party sites are marked estimate. Efficiency and headroom values in the calculators are labeled assumptions you can change. Methodology.