What size portable power station do you need for a router, fridge and smart home?
Updated
Size a power station in watt-hours, not by the box. Add up what you run, multiply by hours, then allow for losses. Examples for a router, a refrigerator and a freezer included.
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The formula: watts times hours
Power stations are rated in watt-hours (Wh), which is how much energy the battery holds. The Department of Energy gives the standard formula for estimating energy use: wattage times hours of use per day, divided by 1,000, gives kilowatt-hours. For a power station you can skip the division and work in Wh: watts × hours = watt-hours needed.
Not all of the battery’s rated capacity reaches your devices. The inverter and conversion lose some, so a common rule of thumb is to plan on roughly 80–85% of the rated capacity being usable. That is a general estimate, not a specification; check your unit’s manual. Add that cushion when you size.
Find your real wattage
Check the label on each device, but treat label numbers as maximums. The DOE describes plugging a device into an electricity usage monitor to measure it, and notes that such monitors cost about $25–$50 and work for 120-volt devices. A plug-in meter, or a smart plug with energy monitoring such as in our smart plug energy monitoring guide, gives you the real figure for your own router, modem and refrigerator.
Refrigerators cycle on and off. The DOE says you can estimate a refrigerator’s running time by dividing the time it is plugged in by three. So a refrigerator that draws 150 W while running uses about 150 × 24 ÷ 3 = 1,200 Wh in a day.
Three worked examples
These are examples with round numbers. Replace them with your own measurements.
| What you run | Example load | Hours | Energy | Power station to look for |
|---|---|---|---|---|
| Router + modem + hub | 30 W | 12 h | 360 Wh | 500 Wh class |
| Above + laptop and phone charging | 80 W average | 12 h | 960 Wh | 1,000–1,200 Wh class |
| Refrigerator alone (150 W running, cycles) | 150 W × 24 h ÷ 3 | 24 h | 1,200 Wh | 1,500–2,000 Wh class |
| Router set + refrigerator | 30 W × 24 h + 1,200 Wh | 24 h | 1,920 Wh | 2,000+ Wh class, or limit the hours |
Now apply the loss cushion. For the last row, 1,920 Wh divided by 0.8 means you want a station rated for about 2,400 Wh to run everything for a full day.
Check the surge rating, not just capacity
A refrigerator’s compressor draws a short surge when it starts, usually several times its running wattage. The inverter has to handle that spike. The inverter’s continuous watts and its surge watts are listed on the spec sheet. Make sure continuous output covers the sum of everything you plug in at once, and that surge output covers the compressor’s start. If the specs are unclear, look at the appliance’s nameplate for its amps and ask the manufacturer.
Do you need to power the fridge at all?
For a short outage, maybe not. FoodSafety.gov says a refrigerator keeps food safe for up to 4 hours if you keep the door shut, a full freezer holds a safe temperature for approximately 48 hours, and a half-full freezer for about 24 hours. Many households spend their battery on the router and phones, then run the fridge or freezer for an hour or two each several hours, with doors closed otherwise. A thermometer in each helps; our refrigerator and freezer temperature alarm guide shows how to get an alert.
Safety and setup
- Use the power station indoors only as the maker directs, away from heat, with room for ventilation.
- Never run a gasoline generator indoors or in a garage. The CPSC says to use generators outside only, at least 20 feet from the home, with exhaust facing away.
- Keep a CO alarm on every level and outside sleeping areas if you ever run a fuel generator. See where to place CO detectors.
- Do not back-feed your house wiring through an outlet. A transfer switch or interlock must be installed by a licensed electrician and follow local code.
- For medical equipment, talk to your doctor or equipment supplier about backup power; do not depend on a general-purpose unit.
If you only need to keep the internet up for a few hours, a small UPS is cheaper and switches over without a blip. The UPS runtime calculator shows how long, and the power outage backup kit lists the other pieces.
Shop by need
Router, modem and phones for a few hours
What to look for: 300–600 Wh capacity, AC outlets with pure sine wave output, USB-C power delivery, pass-through charging
Typical price: $250–$500
See options on AmazonRouter set plus a freezer or fridge for a day
What to look for: 1,500–2,500 Wh capacity, inverter surge rating at least 3 times the appliance running watts, expandable batteries
Typical price: $1,000–$2,200
See options on AmazonJust measuring first
What to look for: plug-in electricity usage monitor that shows watts and kWh, 120 V, max load of 1,800 W
Typical price: $15–$40
See options on AmazonFrequently asked questions
How many watt-hours do I need to run a router?
Measure it, because it varies. As an example, a router and modem drawing 30 W together would run about 8 hours from a 300 Wh battery after allowing for losses. A plug-in meter gives your real number.
Can a portable power station run a refrigerator?
Yes, if the inverter handles the start-up surge and the battery is large enough. A refrigerator cycling at 150 W running uses about 1,200 Wh in a day, so plan 1,500 Wh or more, plus a cushion.
How long does food last in a power outage?
FoodSafety.gov says a refrigerator keeps food safe for up to 4 hours with the door shut, a full freezer for about 48 hours and a half-full freezer for about 24 hours.
Is a power station better than a UPS for my router?
A UPS is cheaper and switches over instantly for a router and modem. A power station holds more energy and can run other devices, but takes more setup and may have a brief switchover unless it has UPS mode.