I’m a senior staff writer at Wirecutter covering batteries, chargers, and charging technology. I’ve been a science journalist for more than a decade, covering a wide variety of topics from particle physics to satellite remote sensing. Since joining Wirecutter in 2017, I’ve reported on surge protectors, power strips for travel, and more.

For this guide:

• I spent 74 hours researching and testing UPS units.
• I worked with Lee Johnson—an electrical engineer with more than 15 years of experience designing and testing electronics—to determine the surge-protection capabilities of each UPS.
• Like all Wirecutter journalists, I review and test products with complete editorial independence. I’m never made aware of any business implications of my editorial recommendations. Read more about our editorial standards.

An uninterruptible power supply, or UPS, is basically a surge protector, battery, and power inverter—which turns the battery’s stored energy into usable power—wrapped into one unit. The size of the battery determines how long the UPS can provide power, and the inverter determines how much power it can put out at a time, a measurement often listed as volt-amperes (VA) but more easily discussed as watts (W).

A small, inexpensive UPS is great for anyone who wants their home Wi-Fi and internet to stay online during short power outages or brownouts. Unlike landlines, which work without power, digital phone service and Wi-Fi require a broadband modem, which may have only a small battery backup. Adding a UPS can keep you online and connected for an hour or more in case you need to reach emergency services—or if you’re about to finish a critical encounter in Elden Ring.

UPS units with extra power and features can help keep home offices and workstations running during business hours, or at least long enough for you to save your work and safely shut down vulnerable equipment. If you have a lot of important data on a desktop computer, an external hard drive, or network-attached storage, you may need a UPS to prevent your drives from losing data in the event of a sudden power outage. In some cases, a UPS can provide crucial backup power to household medical equipment—such as CPAP machines for sleep apnea—for a limited time.

Powering your home theater for a movie marathon during a storm is more difficult, and costlier, than simply buying a UPS. If you need long-term power, the capacity to keep refrigerators and other appliances plugged in, or a way to light up your whole house in blackout situations, you should consider off-grid options with longer run times, such as a portable power station, a generator, or a professionally installed battery-backup system.

We started by considering more than 100 models from three leading companies: APC, CyberPower, and Tripp Lite by Eaton. We also added a few models from Amazon Basics to our list because it’s a prominent option when you’re shopping online.

We considered the most important traits of a great UPS and developed the following criteria:

• Automatic voltage regulation (AVR): Also called line-interactive topology, this is a more advanced form of power management that uses a small transformer as a buffer to compensate for power dips and surges without relying on the battery. This method reduces wear and tear on the battery, especially from frequent brownouts, and provides more reliable power to sensitive gear such as hard drives.
• At least four battery-backed outlets: All outlets on a UPS should provide surge protection, but generally only half the outlets are connected to the backup battery so they can stay on when the power goes out. A set of four battery-backed outlets is enough for you to plug in a modem, router, desktop computer, and external hard drive, so we made that our minimum requirement.
• At least a 5-foot cord: A long cord is helpful if your work area isn’t directly adjacent to an outlet. Keep in mind that it’s unsafe to plug a UPS into an extension cord.
• Rated for at least 600 VA output: Most models list their rated output in volt-amperes (VA), which is a measurement of DC power. We required a rating of 600 VA or more for all models and 1,000 VA or more for upgrade-pick contenders.
• User-replaceable battery: We tested only those models with a user-replaceable battery (video), which allows you to spend only $30 to $60 on a new battery in the future instead of having to buy a whole new UPS.
• Power-management software: We required each model to offer a downloadable application to monitor and manage the UPS from a phone or computer. Such software should also allow you to program the UPS to complete a series of tasks before shutting down if you’re away from your computer when the power goes out—which is especially handy for units with shorter run times.
• Backlit screen: Most UPS units have a small status light, but some pricier models have a helpful screen to display additional information such as the battery’s charge status, the current load, and the remaining run time.
• USB ports: Having at least one USB port lets you charge a phone or other small device without taking up one of the outlets. These ports aren’t surge-protected, though, and since they’re not connected to the battery, you can’t use them during a power outage.
• Pure sine-wave inverter: No model we tested with this feature could match the output, run times, and surge-protection capabilities of our picks, but it can be useful in rare cases, and we generally prefer it—especially in models lacking AVR. All sine-wave inverters turn DC power into AC power, but a pure sine-wave inverter can produce electrical waveforms as clear and smooth as the AC power from any wall outlet, whereas modified (or simulated) sine-wave inverters produce choppier waveforms. A pure sine wave is important for anything with a powerful motor (such as a corded drill, vacuum, or blender), as well as sensitive audio equipment and medical devices that require pure AC power.

• At least a one-year warranty: Most brands whose models we looked at back their devices for upwards of three years, but a year is plenty of time to test out your UPS and determine whether it’s working properly.
• Cost under $300: You can get a good UPS for well under $300, and most models we tested cost less than $200. We gave preference to cheaper models, all else being equal.

We then tested the performance of each model in a few key areas, including the following:

• Battery capacity: Manufacturer run-time ratings outline how long a UPS can keep devices of various wattages running. Since most ratings are based on ideal conditions, we tested our top candidates at two different loads to see how they would perform in real-world use: 20 W, representing the combined power draw of a household modem and router, and 300 W, representing the power usage of a modem, router, PC, and external hard drive running simultaneously.
• Peak power output: To test the maximum load that each UPS could handle, we turned on each one and then unplugged it, leaving it running on its battery. We then plugged in household appliances of known wattages one by one until the battery overloaded and the UPS shut down.
• Surge protection: Applying the same equipment and protocol we use to test surge protectors, we zapped each UPS with 5,000-volt power surges, measuring how many volts they let through. A lower let-through voltage (also called clamping voltage) is better, since you want as few volts as possible to reach your devices.
• USB output: For models with USB-A or USB-C output ports, we connected a USB load tester rated for up to 150 W to each port, cranked up the power until the ports overloaded and the load tester shut down, and recorded the total output in watts.
• Design: We sought out models with a compact size and shape—easy to tuck under a desk or beside an entertainment center—and a streamlined, unobtrusive exterior. We also assessed their build quality, ease of use, and any additional features or included accessories.

The CyberPower CP900AVR has premium features that you typically find in units costing twice as much. It has 10 surge-protected outlets—five of which are battery-backed—and more than double the output necessary to power a household modem, router, PC, and external hard drive. It can keep a typical household modem and router running for up to four hours. It offers must-have features such as automatic voltage regulation, it’s easy to use, and it fits comfortably under most workstations.

It offers great battery life. The CP900AVR surpasses most models we tested in run time. Judging from our testing, we expect it to keep a modem and router running for up to four hours—or to keep a modem, router, PC, and external hard drive running for about 17 minutes—which gives you ample time to save any work and close any programs you have open.

Those results aren’t far behind what we got from our upgrade pick, and they’re more than twice as long as what we saw with our budget pick.

It treats your devices gently. Since this UPS has automatic voltage regulation (AVR), it doesn’t need to transition from wall-outlet power to battery power as often as models lacking that feature. AVR technology provides more-reliable power to connected devices that can’t tolerate power drops, such as hard drives, and it should extend the overall life of the unit.
It has plenty of outlets. The CP900AVR has a total of 10 outlets, including five battery-backed outlets, so you could keep a PC, monitor, NAS, modem, and router running for a while after the power goes out. Aligned in two rows, the outlets are spaced widely enough for you to fit most plugs, and two of them can accommodate even the bulkiest of plugs.

It has one of the longest cords of the UPS units we tested. This UPS has a thick, flexible 6-foot cord, and the flat, low-profile plug is oriented at a 45-degree angle so it won’t block more than one wall outlet.

It’s super powerful. In our testing, the CP900AVR achieved a higher peak power than any comparably priced competitor, and it was just as good as some pricier units we tested.

We were able to plug in 738 watts’ worth of devices—two lamps, a fan, 10 halogen bulbs, and even a KitchenAid mixer set to medium power—before its battery finally cried uncle and shut down.

Most people won’t be powering their KitchenAid mixers on a UPS during a blackout (and you probably shouldn’t, as doing so puts unnecessary strain on the battery). But our test is a good indicator that this UPS can power almost anything you need in your home office for at least a short while.

It offers ample surge protection. In our testing, the CP900AVR knocked down our 5,000-volt surges to just 540.4 volts. That result isn’t quite as good as what we saw from our favorite surge protectors—none of which let through more than 300 volts in testing with identical equipment and parameters—but it’s on a par with how our other UPS picks performed, and it indicates that this UPS can protect your devices against most household power spikes, sags, and surges.

It has a user-replaceable battery. When this UPS’s battery dies, you can swap it out yourself within minutes, rather than replacing the entire unit.

It has its own software. CyberPower’s PowerPanel Personal power-management software is available as a free download with all its UPS models. The utility alerts you when power outages occur and lets you manage automatic and scheduled shutdowns, track the power consumption of your UPS, and check the battery’s charge status and remaining run time.

It’s intuitive to use. This model is as easy to use as any UPS we’ve tested. It has a large, round button on the front to power the unit on and off, and another to mute the notification noises. When the volume is on, the unit issues a double-beep every 30 seconds after an outage, rapid beeping when the battery is about to die, a constant tone in the event of an overload or short circuit, or a beep every two seconds to indicate another internal problem.

Below those buttons is a cluster of four small LEDs that light up to indicate (clockwise from top left) when the unit is powered on, when the battery backup has kicked in, when the unit is overloaded, and when the AVR feature has kicked in. The unit has large vents on either side to prevent overheating, and all of the ports and connectors are located on the back.

It’s fairly compact. The unit has an upright design and dimensions that are about the same as a family-size box of cereal, so you can easily stash it next to a PC tower or wireless router at a workstation, or alongside the speakers and stereo receiver in a record-player setup.

It has lots of convenient extra features. The CP900AVR has a small LED on its backside to alert you if it detects a wiring fault in the outlet you plug it into. It also has a red button to reset the internal circuit breaker in the event of an overload or short circuit.

It lacks USB-A and USB-C ports, but it has a USB-B port and comes with the corresponding cable. This allows you to connect the UPS to your computer, so you can use CyberPower’s software or your computer’s operating system to set up data saving, monitoring, and other functions.

It has two coaxial connectors for hooking up a cable box or modem, as well as a serial port for a printer or other peripheral device. It also offers two network ports for you to connect the unit to a server, a Wi-Fi router, or any other device that requires a wired network connection.

It’s a safe buy. Costing $140 at this writing, the CP900AVR falls well under our $300 price cap. CyberPower backs it with a three-year warranty, which is as long as any coverage we’ve seen and gives you more than enough time to see if the unit works properly and meets your needs. Since power outages happen about once or twice per year on average in the US, you’ll likely have used it in a few real-world outages in that time frame.

Flaws but not dealbreakers

• The CP900AVR has two fewer outlets than our other picks, but 10 outlets is plenty for most people—and all the models we tested with more outlets had worse peak power or run times.
• This model isn’t as easy to slide under a desk or an entertainment center as units that are flatter in shape, like our budget pick, so you need ample vertical space to accommodate it.
• Its ports are also less accessible since they’re located on the back of the unit instead of on top, but that’s a tolerable trade-off to reduce cord clutter.
• Like our other picks, this UPS has a modified sine-wave inverter, so it produces a slightly choppier electrical waveform than what you can get from the pure sine-wave inverters in some models. Those models are better for powering sensitive equipment, but none that we’ve tested excel in more critical areas, such as peak power output or run times.

If you want more outlets, higher power output and battery capacity, and niceties such as an informative screen and USB ports—and don’t mind spending a bit more—the CyberPower CP1350AVRLCD3 is a step up from our top pick.

It offers great run times. In our testing, the CP1350AVRLCD3 kept a 300 W load running for 21 minutes and kept a 20 W load running for 4.5 hours—just a bit longer than our top pick.

It has more outlets than our top pick. With a total of 12 outlets, including six battery-backed outlets, this UPS can keep even more devices running during a power outage.

It shares our top pick’s most critical features—and its flaws. Like our top pick, the CP1350AVRLCD3 is equipped with automatic voltage regulation (AVR), has a user-replaceable battery, and comes with its own software.

But also like our top pick, it uses a modified sine-wave inverter. That’s fine for general use, but it means you shouldn’t use this UPS with sensitive equipment that needs a pure sine wave. That said, none of the models we tested with a pure sine-wave inverter offered the same run times and range of features as this UPS.

It has a wide variety of ports and connectors. Like our top pick, this model has two coaxial connectors and two ethernet ports. Plus, it adds USB-A and USB-C ports (one apiece) so you can charge two small devices, such as a phone and a pair of wireless headphones. It doesn’t have telephone ports, but that’s true of most models we tested, including our other picks.

It has a long cord. Like our top pick, this UPS has a 6-foot cord, which is helpful for placing the unit where you need it most. Also like that model, it has a flat plug that angles to the right, which makes plugging in another device alongside it on a wall outlet easier.

It delivers plenty of power. The CP1350AVRLCD3 has an impressive 1,350 VA rating, which was reflected in our testing—we measured a total output of 825 W. That should be more than enough to power your key devices in a home office or entertainment center.

It has good surge protection. In our testing, this model blocked all but 526.8 of the 5,000 volts we threw at it, showing that it’s capable of protecting devices from most household power surges.

It has a helpful screen. Unlike our other picks, the CP1350AVRLCD3 has a backlit screen, so you can easily monitor what the UPS is doing at a glance. The screen is easy to read thanks to colorful icons and large text, and it displays useful information such as the input voltage, the output wattage, and how much battery life remains.

It has a sleek and practical design. Like our top pick, the CP1350AVRLCD3 stands upright, so you can easily place it alongside your desk. It’s slightly bigger than that model, mostly to accommodate its extra outlets and screen, but still relatively compact. It weighs 22.8 pounds.

It has a circuit-reset button, as well as a small light to indicate a wiring problem with the outlet your UPS is plugged into. It doesn’t have a surge-protection indicator light, but that’s true of most models we tested, including our other picks—just make sure to replace this or any other UPS every three to five years, when the surge protection will have likely worn off.

It has a good warranty. Like our top pick, this UPS is backed by a three-year warranty, and the company’s customer support is fast and responsive in case you run into any issues.

It’s not cheap, but it’s still a good value. Costing $180 at this writing, the CP1350AVRLCD3 is hardly an impulse purchase. But since other contenders with a similar array of features often cost more, and you’ll likely be using it to protect hundreds of dollars’ worth of gear, it might be worth the splurge.

The Amazon Basics Standby UPS 800VA is a good option if your budget precludes you from getting one of our other picks. But in saving some cash, you give a few things up: It has the lowest capacity and peak power output of any of our picks, as well as the shortest cord and the skimpiest warranty. And don’t plan on using it to protect electronics that require either a pure sine-wave inverter or automatic voltage regulation (AVR), since it lacks both features.

It keeps devices powered long enough for you to shut them down safely. If you just want to keep your Wi-Fi network powered during a blackout, this UPS can do so for around 1.5 hours (that’s how long it lasted with our 20 W fan).

But if you need to power more electronics, beware: When we put it under a heavier, 300 W load, we measured a run time of just 6 minutes.

It has lots of outlets. This UPS has 12 outlets total to plug your electronics into, including six battery-backed outlets to protect some sensitive devices—such as a router, modem, laptop, monitor, external hard drive or NAS, and alarm clock—in the event of a power outage. That’s two more outlets than our top pick offers, and as many as our upgrade pick provides.

The cord is on the shorter side, but it has an angled plug. This UPS has a 5-foot cord, which is a foot shorter than those of our other picks, so you might have to move your workstation closer to an outlet to help it reach. But as on our other picks, the plug has a flat profile and angles to the right, making space for other plugs on your wall outlet.

It’s powerful. In our testing, this inexpensive option had more than enough power output to support home-networking gear or a simple home-office setup. We measured a peak power output of 470 W, as it allowed us to connect an assortment of eight halogen bulbs and two lamps to its battery-backed outlets before it tapped out a few seconds later.

That’s a lower peak output than what we got from most of the UPS units we tested, but it should still be enough to power a desktop computer, a household modem, a Wi-Fi router, an external hard drive, and maybe a few small devices.

It provides the best surge protection of any UPS we’ve tested. When we zapped this unit with 5,000 volts, it blocked all but 402.8 of them. Although that’s about twice as many volts as our favorite surge protectors let through, it’s still better surge protection than we’ve seen from any other UPS.

This means that, unlike with some models we tested, on this unit your precious devices should have ample protection against common household power fluctuations as well as against less-frequent blackouts that trigger the battery backup.

It’s compact yet roomy. This unit is about the size and shape of a dictionary laid flat, and at just over 9 pounds, it weighs about half as much as our other picks. At the same time, the outlets are widely spaced, and four of them have enough space for extra-large power bricks.

It has some handy features, though it’s missing a couple of big ones. Like our other picks, this model has a circuit-reset button and a user-replaceable battery, and it comes with free downloadable software. But on the downside, it lacks AVR, its only auxiliary connector is a USB-B port, and like our other picks it has a modified sine-wave inverter.

It isn’t the most intuitive model to use, but it gets the job done. Since a single on/off button on top doubles as all of the indicator lights for the unit, you might need to resort to the manual (or this guide) to figure out what the UPS is trying to tell you.

In short, the button turns solid green when the device is powered on and working, it flashes and beeps when the UPS is running on battery, and it turns solid and plays a constant tone when the battery is overloaded.

The warranty is shorter than we’d like. Compared with the coverage on our other picks, this model’s one-year warranty offers little wiggle room. So if you do choose this model, make sure to test it out within that window to confirm that it works—and continue to test the battery periodically by unplugging the UPS from the wall and letting it run on its battery.

You can’t beat the price. While most models we considered cost $100 or more, this Amazon Basics UPS typically costs just $80.

Use your UPS with the right equipment: It’s important to know what a UPS can and can’t do. Using a UPS for power-hungry devices—such as a laser printer, paper shredder, or space heater—can damage its internal components, degrade its battery, and void its warranty. Small electronics or office equipment without moving parts should be fine, but for anything bigger than a desktop computer, check the manual for your UPS.

Never plug a UPS into a surge protector or vice versa: Aside from potentially overloading either unit and tripping a fuse or breaker, you also risk cancelling out the surge protection instead of doubling it up.

Never plug a UPS into an extension cord: The excess load can cause it to overheat and melt. If the cord on your UPS isn’t long enough, you’re better off moving your workstation closer to an outlet or spending $100 or so to have an electrician install a new outlet—either of which is preferable to replacing damaged electronics or starting a fire accidentally.

Test the battery from time to time: The sealed, lead-acid battery inside your UPS will stay charged as long as the device is plugged in, so it should be able to perform well for many years. But since batteries degrade over time, you can avoid any surprises in the future if, once a year or so, you unplug the UPS from the wall outlet with your devices running—just to make sure the UPS powers them for as long as you expect it to.

Replace the battery, not the unit: Like all electronics, a UPS won’t last forever. But ideally, you should be able to replace the battery numerous times before you have to replace the entire unit. CyberPower sells replacement batteries for our top pick and upgrade pick, as do some third-party battery makers.

Amazon Basics doesn’t sell spare UPS batteries, but you can get a compatible replacement for our budget pick from Duracell, Mighty Max, and other well-established brands. When in doubt, make sure the voltage and terminals (either F1 or F2) listed on the label match the battery that came with your unit.

Recycle old batteries: When you replace the battery in your UPS, you should recycle the old one. We have guidance in a separate article on how to safely and easily recycle used batteries.

If our budget pick is unavailable and you want something that costs less than our other picks: Get the CyberPower AVRG900U. It performed better than our budget pick from Amazon Basics in our run-time tests, keeping a 300 W load running for 6.5 minutes and a 20 W load running for 2.5 hours. It also has a longer warranty (three years compared to a single year) and adds AVR, coaxial connectors, ethernet ports, and a fault/ground indicator light.

On the downside, it has inferior surge protection (blocking all but 554.8 volts, as opposed to 402.8 volts) and costs more at this writing.

If our upgrade pick is unavailable, or you want something with better run times, more surge protection, and a longer warranty: Get the CyberPower BRG1500AVRLCD2. In our run-time tests, it kept a 300 W load running for 22.5 minutes and a 20 W load running for 5 hours, and it blocked all but 516.4 volts in our surge tests. And it’s backed by a five-year warranty, which is longer than that of most models we tested.

However, it lacks coaxial connectors, and it’s one of the priciest models we tested, costing $260 at this writing.

If you absolutely need a UPS with a pure sine-wave inverter: Get the APC BR1500MS2. It’s one of the few models we tested with a pure sine-wave inverter, so you can use it with an even wider range of devices than our picks.

It has 10 outlets, including six battery-backed outlets, and a 6-foot cord. It also offers premium features such as AVR, a user-replaceable battery, an easy-to-read screen, and two USB ports (one USB-A and one USB-C), and APC backs it with a three-year warranty.

In our run-time tests, it kept a 300 W load running for 21 minutes and a 20 W load running for 4 hours. It has a 900 VA rating, and we measured a maximum output of 847 W.

However, we decided not to make it a pick because it performed poorly in our surge tests, letting through just 593.2 volts in the neutral line but leaving its other two power circuit wires unprotected. It’s also expensive, costing $280 at this writing.

This is not a comprehensive list of all UPS units we’ve tested. We have removed any models that are discontinued or do not meet our criteria.

In our testing, the APC BE700G3, the APC BE900G3, the Tripp Lite by Eaton AVR750U, the Tripp Lite by Eaton BC600R, and the Tripp Lite by Eaton BC850R each provided surge protection in only one of their three power circuit wires, leaving the other two unprotected.

We dismissed several models because they let through more voltage than our picks in our surge-protection testing: The APC BE650G1 let through 684.4 volts, the CyberPower CP685AVRG let through 718 volts, the CyberPower CP800AVR (our former runner-up pick) let through 756 volts, and the CyberPower CP1500PFCLCD (our former upgrade pick) let through 628.4 volts.

The Amazon Basics Standby UPS 600VA had a mediocre battery capacity: In our testing, we measured a 30-minute run time at a 20 W load and three minutes at a 300 W load. Plus, it has only eight outlets (four with battery backup), fewer than any of our picks.

The CyberPower CP1000PFCLCD had a shorter run time (90 minutes at a 20 W load, 6 minutes at a 300 W load) and a lower peak power output (535 W) in comparison with either of the similarly priced models we tested, as well as some models that cost less than half as much.

The CyberPower CP1500AVRLCD3 is on a par with our upgrade pick in most respects, and it performed slightly better in our run-time tests, keeping a 300 W load running for 21.5 minutes (versus 21 minutes) and a 20 W load running for 4.8 hours (versus 4.5 hours). However, it lacks coaxial connectors and costs about $10 more at this writing ($190).

This article was edited by Ben Keough and Erica Ogg.