Keep Wi-Fi on in a blackout
A small 300 watt-hour box keeps a 15-watt Wi-Fi router on for about 17 hours, as long as your internet provider's network still has power.
By our math, a small box of 300 watt-hours keeps a 15-watt Wi-Fi router on for about 17 hours. Your internet also needs your provider's network to have power, and no box in your home can fix that. Watt-hours: how much power a box holds. Watts: how fast something uses power.
What to plug in
Follow the cable from the wall to your Wi-Fi. Every box on that path needs power. You may have one box that does it all. You may have a modem and a router. A home with fiber may have a small fiber box too.
Not sure which box is which? The modem is the one with the cable from the wall. The router is the one that makes the Wi-Fi.
Our tools count 15 watts for a Wi-Fi router. Google lists a 15W power adapter for its Nest Wifi router. TP-Link lists a 12-volt, 2-amp adapter for its Archer AX55. That is 24 watts by our math.
The number on the adapter is the most the router can draw, so real use can be lower. If you have two network boxes, count 15 watts for each. That makes 30 watts.
The easy math
Take the box size in watt-hours. Keep 85% of it, because some power is lost inside the box. Then divide by the watts.
286 Wh × 0.85 ÷ 15 W = 16 hours
That is the EcoFlow RIVER 3 Plus, a small box. With two network boxes at 30 watts, the same box lasts about 8.1 hours.
Want to charge phones too? Our tools count 20 watts for phones. A router and phones together are 35 watts. The same box runs them for about 6.9 hours.
Estimates. Your devices may use more or less.
Hours by box size
Our tools count 65 watts for a laptop. The last column adds one to the router, for 80 watts in all.
| Box size | Router only (15 W) | Modem and router (30 W) | Router and laptop (80 W) |
|---|---|---|---|
| 300 Wh | 17 hours | 8.5 hours | 3.2 hours |
| 500 Wh | 28 hours | 14 hours | 5.3 hours |
| 1,000 Wh | 57 hours | 28 hours | 11 hours |
| 2,000 Wh | 113 hours | 57 hours | 21 hours |
Wi-Fi is a small load. That is why it lasts so long. If you want to add a fridge or lights, Find My Power does the math for your whole list.
Will the internet really stay on?
A box only powers the gear inside your home. Your provider's network needs power too. We cannot tell you if it will stay up where you live. Ask your provider what happens to your service in an outage.
The FCC warns that internet phone service may not work during a power outage or when the internet connection fails. It also says phone service that runs over broadband will not work in an outage without a battery or other backup power.
So keep a second way to reach people. The FCC suggests a cell phone as a backup.
Set it up before the storm
- Find every network box. Read the watts, or the volts and amps, on each power adapter.
- Add them up. Pick the hours you want. Then check the table above.
- Keep the box near your network gear so the cords reach. Label the cords now, so you can find them in the dark.
- Charge the box, your phone and your laptop when a storm is coming. The FCC gives the same tip for phones and laptops.
- Some boxes can sit between the wall and your gear and take over when the power drops. EcoFlow lists a switch-over under 10 milliseconds for the RIVER 3 Plus. We have not checked if a router stays on through that gap.
Not sure which numbers to read on a box? See what a watt-hour is. Then compare two boxes or look at our picks. We read every spec on the maker's own page, and this is how we check.
Questions people ask
How long will a 1,000 watt-hour box run Wi-Fi?
About 57 hours for one 15-watt router, by our math. About 28 hours if you have a modem and a router at 30 watts.
Do I need to power the modem too?
Yes. Every box between the wall and your Wi-Fi needs power. If one of them is off, the Wi-Fi may be on but the internet will not work.
Will my home phone work in a blackout?
It depends on the kind of phone service. The FCC says phone service that runs over broadband needs a battery or other backup power. Ask your provider.
Can I run Wi-Fi and a fridge on one box?
Yes, if the box is big enough. A fridge and a router come to 135 watts by our count. A 1,000 watt-hour box runs that for about 6.3 hours. The box must also start the fridge, and our tools count 1,200 watts for that. So the small box in this guide is not enough for this job. See how long a fridge runs on a power station. For a longer list, read backup power for a whole home.
Estimates. Your devices may use more or less. As an Amazon Associate I earn from qualifying purchases. Made with AI tools for research and drafting. Samuel Guerra reviews every guide and checks it against the sources linked on this page.