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Check off what you want to keep running during an outage, at a campsite or on the job. The calculator adds up running watts, finds your biggest startup surge, and estimates the battery capacity (Wh) and generator size you need. Wattages are typical estimates; check the label on your own appliances for exact numbers. For appliances that cycle on and off (fridges, freezers, heaters), enter the hours they actually run, about a third of the day for a fridge.
| Use | Appliance | Running W | Startup W | Hours on/day |
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How to read your results
- Running watts is what everything uses at the same time. Your power station’s continuous output (or generator’s running watts) must be higher than this.
- Startup (surge) watts matter for anything with a motor or compressor: fridges, freezers, pumps, AC units and furnace blowers can briefly draw 2–3 times their running watts. We add the largest single surge to your running load, since motors rarely start at the exact same moment.
- Watt-hours (Wh) is how much energy you use over a day. Battery capacity is listed in Wh. We add about 15% for inverter losses, so a 2,000 Wh battery delivers roughly 1,700 Wh of usable power.
- Generators are sized by starting watts with a 20% margin so they aren’t running flat out.
Safety notes from the trade
- Never run a gas, propane or dual-fuel generator indoors, in a garage or near open windows. Carbon monoxide is deadly; install CO alarms.
- Never backfeed your home through an outlet. Use a transfer switch or interlock kit installed by a licensed electrician.
- Gas furnaces need a pure sine wave power source; most power stations and inverter generators provide this, but many open-frame generators do not.
FAQ
What size power station runs a refrigerator?
A typical modern refrigerator runs at roughly 100–200 W but cycles on and off, using about 1–2 kWh per day, with a startup surge around 1,000–1,500 W. A power station with at least 1,000 W of output and 1,000–2,000 Wh of capacity can usually keep one running for a day or more.
Can a power station run my furnace?
A gas furnace’s blower and controls usually draw a few hundred watts, so a mid-size power station can run it, but it must be connected properly. Hardwired furnaces need a transfer switch or furnace power inlet installed by an electrician.
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