When the power drops, a desktop computer goes dark instantly, the router reboots, and the call you were on is gone. A UPS (uninterruptible power supply) bridges that gap: it switches to battery in a few milliseconds and gives you time to save, finish the call, or shut down cleanly.
This guide is written by an engineer who builds energy monitoring systems for sites that run on batteries and generators. The physics is the same on a desk: watts, watt-hours, and how fast the switch happens.
How We Chose
We read the official datasheets and product pages, and we kept the figures that matter for a home office.
- Power rating: watts (W), not only VA. Your equipment draws watts.
- Topology and waveform: standby or line-interactive, simulated or true sine wave.
- Outlets: how many are battery-backed, and how many are surge-only.
- Switchover time: how long the output is interrupted when the grid fails.
Step 1: add up the watts you need to keep alive
List what must stay on during an outage, then add their power draw. Typical ranges:
- Router and modem: about 10 to 30 W together.
- Laptop on its charger: about 45 to 100 W (the figure printed on the charger is the maximum).
- Desktop computer: about 100 to 400 W depending on the graphics card.
- Monitor: about 20 to 60 W each.
Check the labels on your own devices; a plug-in power meter gives the exact figure. Then pick a UPS whose watt rating is at least 25% above your total, so it is never run at its limit.
Step 2: decide how long you need it to last
A classic UPS gives minutes, not hours: enough to save and shut down, or to finish a call. For a rough runtime estimate on a battery rated in watt-hours, divide the capacity by your load, then keep about 85% for conversion losses:
Runtime (hours) ≈ capacity (Wh) × 0.85 ÷ load (W)
For outages that last hours, look at a portable power station with a UPS function: much more capacity, at a higher price.
Standby or line-interactive?
- Standby switches to battery only when the power fails. Cheap and fine for a router and a laptop.
- Line-interactive also corrects voltage that runs too high or too low without touching the battery (APC calls this AVR). Better if your lights flicker or your area has brownouts.
- Waveform: computers with active PFC power supplies, common in modern desktops, prefer a sine wave output. A "stepped approximation" is fine for routers, laptops and monitors.
Top Picks at a Glance
1. APC Back-UPS Pro BR1500MS2
– Best for a desktop setup
For a desktop computer with one or two monitors, this is the model we would buy. APC's datasheet lists a line-interactive design with a sine wave output, which is what modern desktop power supplies expect, and automatic voltage regulation for brownouts.
It has six battery-backed outlets and four surge-only ones: put the computer, the monitors and the router on the battery side, and the printer or the desk lamp on the surge side. The battery is user-replaceable (APC reference APCRBC163), which matters because lead-acid batteries wear out over the years.
Who it is for: a desktop setup up to a few hundred watts that needs to ride through short outages and voltage dips.
Best for a desktop setup
APC Back-UPS Pro BR1500MS2
- 1500 VA / 900 W, line-interactive
- Sine wave output
- 6 battery-backed + 4 surge-only outlets
- Transfer time 8 ms typical, 10 ms maximum
2. APC Back-UPS BE600M1
– Best for the router and a laptop
If you work on a laptop, the laptop already has its own battery: what drops your video call is the router. A small standby UPS like the BE600M1 keeps the modem and router online, with outlets left for a monitor and a phone charger.
Its output is a stepped approximation to a sine wave, so we would not use it for a desktop with an active-PFC power supply. For a router, a modem, a laptop charger and a monitor, it is all you need.
Who it is for: laptop workers who want their internet to survive a power cut.
Best for the router and a laptop
APC Back-UPS BE600M1
- 600 VA / 330 W, standby
- Stepped approximation to a sine wave
- 5 battery-backed + 2 surge-only outlets
- Transfer time 6 ms typical, 10 ms maximum
3. Anker SOLIX C1000
– Best for long outages
When outages last hours rather than minutes, a power station is the better tool. With 1,056 Wh, the formula above gives roughly 1,056 × 0.85 ÷ 100 ≈ 9 hours for a 100 W laptop-and-router setup.
Anker lists a UPS switch time under 20 ms. That is slower than the APC units above (10 ms maximum), so test it with your own computer before you rely on it for a desktop: most laptops won't notice, since they run on their own battery.
Who it is for: anyone who loses power for hours at a time, or who also wants backup power outside the office.
Best for long outages
Anker SOLIX C1000
- 1,056 Wh capacity
- 1,800 W continuous, pure sine wave
- UPS switch time under 20 ms
- 6 AC outlets, 5-year warranty
4. EcoFlow RIVER 3 Plus
– Compact pick
A smaller power station that sits on a desk. EcoFlow lists a UPS switchover under 10 ms and 286 Wh of capacity: about 286 × 0.85 ÷ 30 ≈ 8 hours for a router and modem drawing 30 W, or a couple of hours with a laptop added.
At the time of writing, the official store showed it on pre-order, so check availability before you plan around it.
Who it is for: a laptop and router setup that needs more than a classic UPS, in less space than a large power station.
Compact pick
EcoFlow RIVER 3 Plus
- 286 Wh capacity
- 600 W rated output (1,200 W X-Boost)
- UPS switchover under 10 ms
- USB-C up to 100 W
Setting it up
- Battery side vs surge side: computer, monitors, router and modem on the battery outlets. Printers, especially laser printers, on the surge-only side: their heaters draw far more than a small UPS can supply.
- Plug the UPS into the wall, not into a power strip.
- Test it once: unplug the UPS from the wall while you work and watch what happens. Better to find out now than in the middle of a call.
- Replace the battery when the UPS asks for it. Lead-acid batteries typically need replacing after a few years.