What size power station do I need for a power outage?
Updated November 12, 2026
Most people buy either too small or far too big. You only need two numbers to get it right: how many watts your devices use, and how many hours you want them to run.
Step 1: list what you must keep running
Start with needs, not wants. In most homes the outage list is short: the fridge, the internet router, a few lights, phones, and any medical device such as a CPAP machine.
Typical running power for common items:
- Refrigerator: about 100 to 200 watts while the compressor runs, and it only runs part of each hour
- Internet router and modem: about 10 to 20 watts
- LED light bulb: about 10 watts each
- CPAP machine: about 30 to 60 watts, more with a heated humidifier
- Laptop: about 50 to 60 watts while charging
- Phone: about 10 to 15 watt hours for one full charge
Step 2: work out capacity in watt hours
Capacity is measured in watt hours (Wh). Multiply the watts a device uses by the hours you want it to run. A 40 watt CPAP for 8 hours needs 320 Wh.
No power station delivers its full rated capacity, because some energy is lost in the inverter. A fair rule is to count on about 85 percent. So the formula is: run time in hours equals capacity times 0.85, divided by the watts in use.
Example: a 1,000 Wh station running a 100 watt load lasts roughly 8.5 hours.
Step 3: check the output in watts
Output is how much power the station can deliver at one moment. Add up the watts of everything that will run at the same time and make sure the station's rated output is higher.
Fridges and other motors need a short burst of extra power when they start, often two to three times their running watts. Check the station's surge or peak rating as well as the continuous rating.
Quick sizing guide
- Phones, router and lights for an evening: 300 to 500 Wh
- CPAP for one or two nights plus phones: 500 to 1,000 Wh
- Fridge, router, lights and phones for a day: 1,000 to 2,000 Wh
- Several appliances for multiple days, or whole home backup: 3,000 Wh and above, usually with expansion batteries
Plan how you will recharge
In an outage longer than a day, recharging matters more than size. Solar panels are the usual answer. A 200 watt panel in good sun produces very roughly 600 to 1,000 Wh over a day, and much less under cloud.
Before buying panels, check the station's maximum solar input in watts. A station that accepts more solar power refills faster.
This guide gives general information. Always follow the safety instructions that come with your own equipment.