The Best Smart Smoke Alarm

After a new round of testing we recommend our current pick, the Google Nest Protect. A section about security was added, plus a few Competition models.

Smoke alarms will warn you of danger, but not if you aren't home to hear them. (They’re also typically ugly, a pain to shush, and shriek whenever someone burns toast.) Smart smoke alarms are the cure for those shortcomings, and after testing two new combo smoke and carbon monoxide alarms, along with our current pick the Google Nest Protect, we continue to recommend the Nest Protect as the only one worth buying. It sends speedy alerts of smoke or carbon monoxide to your phone and has a wonderful "heads-up" voice warning that lets you mute the siren before it goes off (in the event of a false alarm). It's simple to mute via a button or the mobile app, and, well, it's nice looking. The Protect also constantly self-tests to ensure its sensors are accurate and has a motion-activated path light.

In the event of a false trigger such as from cooking, smart alarms can be muted both by a button but also more easily by using an app.

Many alarms have a 10-year lifespan that is based on date of manufacture. Check the date on the box or unit itself and be sure to buy as new a device as possible.

Smart alarms can integrate with other smart devices. If the alarm is triggered, it can be set to turn on smart lighting or shut down your HVAC to prevent smoke damage.

Tested to UL standards means an alarm has passed the test once, but UL certification means quality control testing is ongoing.

Google Nest Protect's sensitivity to slow- and fast-burning fires, ability to self-test, sleek design, and straightforward app make it the best smart fire-safety device.

*At the time of publishing, the price was $115.

The Google Nest Protect has all the features we recommend in a smart smoke alarm. It can detect both slow- and fast-burning fires, and it wirelessly interconnects with other Protects. The Protect uses voice alerts to warn you which room the danger is in and gives you time to check before it triggers the siren. It's the easiest alarm to silence, through the polished and friendly Nest app, or by pressing the large button in the center of its face. And the Protect is the only model that tests itself—which cuts down on annoying low-battery chirps in favor of useful smartphone notifications should something go wrong. The Protect is available in both hardwired and battery-powered versions, and so should work in any home.

An outdoor security camera can alert you to prowlers, package deliveries, and visitors, as well as to animals in your trash and things that go bump in the night.

A smart doorbell camera allows you to see who's on the other side of your door—even when you aren't home—so you can screen for visitors and package deliveries.

This guide has been substantially rewritten in 2022 by Roy Furchgott. It also contains some existing research and testing by Jennifer Pattison Tuohy.

For this guide we read multiple research papers and spoke with two experts at UL (formerly Underwriters Laboratories), which literally writes the book on testing smoke alarms: Dwayne Sloan, technical director of Built Environment; and David Mills, principal engineer Initiating/Indicating Devices. We also scoured hundreds of customer reviews from sites like Amazon, Home Depot, and Lowe's.

Roy Furchgott handled all testing and research for this update. He has personally reviewed more than 1,000 pieces of consumer technology and more than 500 apps, including a wide array of smart-home devices. His work has appeared in more than 100 publications, including The New York Times, The Washington Post, Business Week, Forbes, and Wired.

Jennifer Tuohy was the previous author of this guide. She is currently the smart-home editor at The Verge.

A smoke and carbon monoxide (CO) alarm is an essential, critical safety device in any home, and because of the added functionality of smart models we think even smart-home skeptics should invest in one (or several). A traditional smoke and CO alarm alerts you to potential danger when you’re at home, but a smart alarm is able to directly contact you even when you’re away—and some can even send word to a trusted contact, too, in case you miss the notification. The ability to remotely contact you makes smart alarms especially great for vacation properties, but also in the homes of loved ones who need extra attention.

Crucially, smart alarms address one of the biggest problems with regular alarms—that an alarm can stop working, either because you knocked it off the ceiling with a broom, never replaced the batteries, or took the batteries out so you wouldn't have to knock it off the ceiling with a broom. According to a 2021 report, almost three of every five home-fire deaths in the US resulted from fires in homes with no smoke alarms or with nonfunctioning ones. Nearly half of the alarms that failed had missing or disconnected batteries, and a quarter had dead batteries. Most smart alarms alert you to their battery level in their apps and let you silence "nuisance" alarms on your phone or via a button on the device (rather than pulling the battery out), so you won't end up with a non-working device in an emergency.

Because a smart alarm can be silenced from your phone, instead of requiring you to climb a ladder or brandish a broom, it reduces the chance you’ll disable it in a fit of annoyance when you’ve burnt the popcorn. Plus, most smart smoke alarms wirelessly interconnect with one another—if one triggers, they all do—which is an excellent safety feature if your home doesn't have an existing hardwired interconnection.

We believe a smart smoke and carbon monoxide (CO) alarm is a crucial safety device for your home, one that even smart-home skeptics should consider.

If you need to replace your smoke alarms, we think the price premium of around $80 for going smart is a small one to pay for the added peace of mind and safety features.

(Note that if you have a professionally monitored security system, you may be better off adding a compatible smoke and carbon monoxide alarm, which will alert the fire department on your behalf if you don't turn off the alarm within a designated period. Because those alarms are part of a comprehensive security system, we didn't include any in our testing or coverage.)

Bear in mind that smoke alarms have a lifespan, and many are designed to die 10 years from the date of manufacture—and not the date of install. That is a UL and NFPA requirement for any alarm with a 10-year sealed battery as its primary power source. Additionally, sensors in some alarms may expire sooner than that, so before buying, always check on the device for its expiration date and only buy ones that are recently manufactured.

An oft-touted feature of smart alarms is that they eliminate the nightmare of the 2 a.m. mystery battery chirps. This is true, but only if you pay attention to the alerts in the app and change the batteries when directed. If you don't, the alarm will eventually beep at you (another UL safety requirement).

If you already have a house full of working smoke alarms, or you simply don't want to pay more for a smart alarm, a smoke alarm monitor may be an option (see Smoke alarm monitors for more info). These devices or services listen for the sound of a regular smoke/CO alarm and then send you an alert on your smartphone. For instance, Alexa Guard, a free feature for all Amazon Echo–branded devices, sends a notification if it hears an alarm, along with an audio recording, and you can even "drop in" on the device to hear what's going on in real time. These devices don't allow you to mute your alarm, but at least they notify you quickly if something is awry at home.

Following our research, we determined that to justify the price premium and provide the best functionality, a smart alarm should:

This last aspect is worth emphasizing, because interconnected alarms can save you precious seconds if you have to evacuate your home. In fact, many states now require interconnected alarms for new construction and some remodels (this can be a wired or wireless communication, as long as it's not dependent on a working Internet connection).

Our pick, the Google Nest Protect, uses its own photoelectric sensor it calls a Split-Spectrum Sensor; the company claims that this detects fast-burning fires more quickly than traditional photoelectric sensors do, without as much risk of false alarms. The new UL standard, 217v8, which goes into effect in 2024, lets manufacturers use an array of proprietary sensors and algorithms to respond more quickly to more sources of fire while going off less often due to cooking.

There are a number of smoke alarms that work with smart security systems. A major benefit to this is that they can be professionally monitored. For this guide, we didn't test them, because they aren't intended to be used on their own. For more on those, read our review of the best home security systems. And though we believe in the importance of remote notifications, self-testing, and early alerts for low batteries, if you’re simply not interested in those smart features, or the cost of smart alarms is too much for you, we also recommend these standard smoke alarms.

A home security system is all about peace of mind. It can alert you to an open door or window, frighten away prowlers, and call for help should you need it.

Testing for our latest round of new and existing pick smart smoke alarms was conducted in a three-level rowhouse. The smoke alarms were subjected to cigar smoke, smoke from extra-long matches, and cooking smoke (pro tip: seared tuna reliably sets off alarms). We monitored smart alerts sent to an iPhone. In assessing each device's companion app, we focused on ease of use and installation guidance, how well and how quickly notifications were sent and received, and the speed and ease of silencing alarms.

Because the reliability of these devices can be of life or death importance, we only considered smoke alarms that meet UL standards for smoke and carbon monoxide (CO) detection. UL tests smoke alarms, smart or not, by the same standard, simulating both fast-burning and smoldering fires.

Wirecutter takes security and privacy issues seriously. To help you understand how the brands we recommend handle your data and information, we read their privacy policies in depth and also have them fill out an extensive questionnaire detailing their policies and procedures. We’ve consolidated the answers Google supplied to us here to make them more readily understandable. (You can read the full answers below in Privacy and security policies.)

The Google Nest Protect doesn't require owners to create a login to use it as a standalone smoke/CO alarm, but if you intend to rely on its smart features (as we recommend) then you’ll need to create a password-protected Nest account and also enable two-factor authentication (2FA is a system to ensure that only you can access your device's settings, by requiring you to input a unique code that is sent to you when you attempt to log in). All user data is encrypted at rest, meaning when it is stored on hard drives in the cloud, and also when it is transmitted to the cloud. Google pledges in its privacy policy that it does not sell or share any Nest consumer data it collects with third parties, which may include your name, email address, or billing information, without your prior permission.

Google Nest Protect's sensitivity to slow- and fast-burning fires, ability to self-test, sleek design, and straightforward app make it the best smart fire-safety device.

*At the time of publishing, the price was $115.

The second-generation Google Nest Protect smoke and carbon monoxide alarm is the best smart smoke alarm for everyone because it reliably and calmly alerts you to potential danger—whether you’re home or away—using a combination of voice, siren, and smartphone alerts. It even sets off a voice warning before the alarm sounds, so you have time to mute it in case you’re sure it's just a false alarm (I’m looking at you, seared tuna). If you have more than one Protect, they interconnect wirelessly, and the Protect also self-tests and informs you of device malfunctions or low batteries via smartphone alerts—without those annoying chirps. You can silence nuisance alarms through the Protect's app, so you’ll be less likely to disable it in a fit of annoyance (as many people do when an alarm starts chirping). The Protect is also the simplest smart alarm to install and control. Note that Nest is releasing an updated version of this model that will be compliant with newer UL standards (specifically UL217v8). To confirm you are buying the newest version, look for a UL217v8 label on the box, or consult the product description for the phrase "Helps reduce cooking nuisance alarms."

Nest Protect uses a photoelectric Split-Spectrum Sensor, which the company claims detects fast-burning fires more quickly than traditional photoelectric sensors—more in line with the performance of ionization sensors. The Protect accomplishes this with a second LED that can pick up the finer particles of fast-burning fires but is less likely to suffer from nuisance alarms.

One of our favorite Protect features, from a livability perspective, is the Heads-Up warning, which gives you a chance to address a situation before a loud siren sends every person and animal in the house into a panic: When it's triggered, the Protect's gentle chime is followed by an announcement: "Smoke is detected in the hallway, an alarm will sound soon, the alarm is loud." We think this is ideal, since it alerts without causing panic. And any nuisance alarms were simple to silence with a gentle press on the Protect's large, easily accessible button or through the app.

The Nest app is also the easiest to use for silencing alarms from the phone. Alerts popped up instantly and gave clear indications as to why we couldn't silence the alarm, if the smoke levels were too high; this was not the case with the other models we tested that offered this feature.

The Protect is packed with sensors, including ones for humidity, room occupancy, and ambient light, on top of carbon monoxide, smoke, and heat. And so its home-automation capabilities are impressive—but, notably, only if you use Google Nest smart-home devices. For instance, if you have a Nest Cam, it will start recording video if an alarm sounds (even without a Nest Aware subscription). A Nest Thermostat will shut down the HVAC system in an attempt to stop a fire from spreading (one of the first things firefighters do when they arrive at a house fire is shut down the heating and ventilation system). Protect's occupancy alarms also feed data about whether you’re home to a Nest thermostat, and it can adjust the temp accordingly. We particularly liked the Pathlight feature—a smart night-light that activates when a room is dark and motion is sensed. During an emergency, it will turn red to help you find a way to safety.

You can also use those sensors to make your home a bit smarter. Hardwired Protect alarms can be added to the Presence Sensing feature in the updated Google Home app (to access it you’ll have to connect your Nest app to the Google Home app, if you haven't already). Presence Sensing uses the Protect's motion sensor, as well as other compatible devices you may enable (including your smartphone, any other Nest thermostats, Nest smart locks, or Nest Secure sensors), to tell if anyone is home, and then it decides whether to enable the Home or Away Routines. These Routines can be customized in the Google Home app to, perhaps, tell lights to turn on or off, set cameras to record or shut off, or adjust the thermostat. Disappointingly, there are no options to use the Protect as a trigger, so you can't set up your smart home to react to fire, smoke, or CO by turning lights on and unlocking doors (as you used to be able to before Google shut down the Works with Nest program).

The Protect is the only alarm we tested that self-tests its sensors, which it does every 200 seconds. It also tests its speaker and alarm once a month during a window of time that you select (and that you can override if it happens to coincide with nap time). A color-changing status light on the Protect lets you know the device is working properly: If it's glowing yellow, press it, and the Protect will say aloud what's wrong (or you can look at the app). This kind of peace of mind is worth a lot, in our opinion.

Installing the Nest Protect is very straightforward. We tested two units, one battery-powered, one hardwired. We used the app (iOS and Android) to scan each device, pair each one with our Nest account, and then assign each Protect to a room. The app and the Protect alarms then performed a mutual test, and the alarms were ready to go on the ceiling (or wall—your preference). For the hardwired alarm, using your existing interconnect wire isn't necessary since Nest uses its own wireless mesh network to connect all your Protect alarms together.

In addition to the standard username and password system for logging in, the Nest app provides far more secure two-factor authentication (2FA), which requires you to input a special one-time-use code, received via email or text, to access your camera and recordings. (For more tips on securing your devices, see our post "How to Protect Your Smart Home From Hackers.")

The Nest Protect is considerably more expensive than a standard smoke and CO alarm: To fully equip a two- or three-bedroom home would cost several hundred dollars for devices with a pre-set lifetime of 10 years. Notably, Nest does offer a discount on multiple devices through its website, as do some other retailers. To economize, some may be content to install just one or two Nests in central areas of a home.

Unlike other Nest devices, the Protect isn't especially integrated into the Google Home ecosystem. That means you have to use the Nest app to set up and control it—not the Google Home app as with other Nest devices. This may be confusing for anyone looking to set up a smart home centered on Google Nest products.

Complaints about battery-powered Protect alarms chewing through batteries in a matter of weeks are somewhat common (this isn't an issue with the hardwired model). We suspect a good portion of those may be people who use standard alkaline AA batteries in them, rather than the more expensive long life lithium ones that Google Nest specifies. The battery-powered Protect uses its batteries for the Pathlight feature, so if you have the Protect in a hallway, frequent activation will drain the batteries more quickly. You can disable Pathlight or set it to the lowest brightness level to conserve battery life. In our test home, we’ve replaced the batteries just once in three years, and that device is installed in a main hallway.

Nest offers only a two-year limited warranty for the Protect, compared with the Onelink Safe & Sound's three-year warranty and the Onelink Smoke & Carbon Monoxide alarm's five-year warranty.

If you already have a house full of smoke alarms that you don't want to replace, or you’re in a rental and not allowed to swap out your smoke alarms, you have another option for getting notifications when your alarms go off: smoke alarm monitors.

These are plug-in devices with microphones that listen for the standard smoke and CO alarms you already have. When they hear one, they send a notification to your smartphone. As a bonus, you may already have a device in your home that can do this.

Amazon Alexa Guard

All Amazon Echo–branded speakers have a free, built-in feature called Alexa Guard. When enabled through the Alexa app and then armed by a voice command, your Echo listens for your home's various smoke alarms and sends an alert to your smartphone if they activate. You receive a push notification from the device that heard the noise (if you have multiple speakers, you may get multiple alerts), saying, "Possible smoke or CO detected in [room your Alexa is in]." You can then tap the notification on your phone to listen to the sound or Drop In on the device to see or hear what's going on. You will then get an alert when the alarm stops.

In our testing, this worked reliably, hearing all the various alarms in our test house. However, you have to remember to enable the Guard feature when you leave—you can do that in the app or by saying "Alexa, I’m leaving." You also need one Echo device in each room for it to work reliably. As a bonus, Alexa will also listen for sounds of glass breaking, as well as integrate with your Ring or ADT alarm system. (Note there is also a subscription version called Alexa Guard Plus, but we don't think it's worth the investment.)

Ring Alarm Smoke & CO Listener

If you already have a Ring Security System, the $35 Ring Alarm Smoke & CO Listener is an inexpensive way to turn your existing smoke alarms smart. The Listener triggers when it hears another smoke or CO alarm. In testing it worked very well, and we liked that it not only sends an alert to your phone but it also triggers the Ring Alarm Base station siren, which is a loud 104 decibels—louder than most smoke alarms and much louder than any other monitor we tested. But in order for it to work, you need to mount a Listener by each of your smoke alarms, which can add up quickly in a large home.

The Owl Wired is unique among smart smoke alarms, as an all-in-one wired smoke, CO, motion, noise, temp, and humidity alarm. It can interconnect with traditional wired alarms but so far does not yet support integration with smart platforms like Amazon Alexa, Apple HomeKit, or Google Assistant (Owl says those are coming). More important, Owl says that while the Wired smoke alarm has passed UL testing, for complex business reasons it does not have official UL certification. We will hold off reviewing it for now.

The Kidde Smoke + Carbon Monoxide Alarm is a promising alternative to the Nest Protect, but still has some bugs to work out. The hardwired units installed easily and can integrate with many other hardwired Kidde alarms if you want to augment your system with less expensive smoke alarms. In a test, it also worked with the hard wired Firex smoke alarms I had previously installed. Both units reliably called out "Fire!" in tests, and the "hush" button shut down cooking-activated false alarms easily. It also has an option to message others when the alarm sounds. The premium Kidde Smoke + Carbon Monoxide with Indoor Air Quality, adds sensors for humidity, temperature, and volatile organic compounds. It works with Google Assistant and Amazon Alexa, but it was not easy to set up and does not run automation routines. There were flaws that Kidde is still working out—our unit was stamped with a QR code for a different model (according to support), which put a hitch in installation.

Although we strongly recommend the Nest Protect for most people, if you’re looking for a HomeKit-compatible alarm, or want to avoid the Google Nest ecosystem altogether, First Alert's Onelink brand is currently your best option. There are two models. First Alert's Onelink Smoke & Carbon Monoxide Detector (second-gen) and First Alert's Onelink Safe & Sound. Both can trigger Homekit automations and while Alexa compatible Onelink can't trigger Alexa Routines. Neither Onelink alarm has an early warning feature. There's also no built-in self-testing feature, but you can test the alarm through the app. The hardwire-only First Alert's Onelink Safe & Sound is our favorite model of the two because it triggers automations more quickly than its sibling, which was also prone to false alarms. At $250 list, it's a very expensive smoke and CO alarm, the fact that it has a built-in Alexa voice-controllable speaker that doubles as an AirPlay 2 speaker helps cushion the sticker shock. The First Alert's Onelink Smoke & Carbon Monoxide alarm (second-gen) is a less expensive, more traditional alarm that comes in hardwired and battery versions. It offers room-specific voice alerts, a color-changing LED ring that flashes during an emergency, and wireless interconnection with other Onelink alarms (the wired version can connect to a variety of other alarms, too).

The First Alert Z-Wave Smoke & Carbon Monoxide Alarm (ZCOMBO) is battery-powered only (there's no hardwired mode), doesn't offer voice alerts or self-testing, and, unlike Protect, it has no wireless interconnectivity with other alarms.

The $40 X-Sense Wi-Fi Smoke alarm is a connected smoke alarm that is set up and managed using the Tuya smart app—it's not compatible with smart home platforms like Alexa, Google Assistant or HomeKit—and it can send smartphone alerts when an alarm is triggered. It also does automatic self-testing of its battery and power connections, and can be silenced through the app. The X-Sense doesn't detect CO, which we think is a feature that every modern smoke alarm should have. While the company says it conforms to UL standards, it's not yet UL-certified. We will keep an eye on X-Sense and whether new models may be worth testing.

Yes/No

No. Updated information on Nest sensors can be found here.

This article was edited by Jon Chase and Grant Clauser.

Dwayne Sloan and David Mills, Technical Director Building and Life Safety Technologies, UL and Principal Engineer Initiating/Indicating Devices, UL, phone interview, August 10, 2021

John Drengenberg, Consumer Safety director, UL, interview, September 1, 2016

Dan Kaiser, , Smoke Alarms and Smoke Detectors – New and Revised Requirements, UL, December 14, 2020

Joan Engebretson, What You Need to Know About the New Smoke Detector Standards, SDM Mag, October 22, 2020

Marty Ahrens, Smoke Alarms in US Home Fires, National Fire Protection Association (NFPA), February 1, 2021

Planning and Implementing a Successful Smoke Alarm Installation Program (PDF), NFPA

Roy Furchgott

Roy Furchgott has personally tried more than 1,000 pieces of consumer technology and more than 500 apps. Roy's work has appeared in more than 100 publications, including The New York Times, The Washington Post, Business Week, Forbes, Outside, and Wired. In addition, Roy has won awards regionally and nationally for writing and regionally for photography.

Jennifer Pattison Tuohy

Jennifer Pattison Tuohy writes about smart-home technology use and sustainable living, while trying to practice both (one is a lot easier than the other).

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