Best Smart Smoke and CO Alarms in 2026 (Now That Nest Protect Is Gone)

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A regular smoke alarm only helps if someone’s home to hear it. A smart one sends an alert to your phone the second it goes off, whether you’re at work, on vacation, or asleep two floors up. It also tells you which room has the problem, warns you when a battery’s low before it starts chirping, and lets you silence a burnt-toast false alarm from the couch.

For years the easy answer was the Google Nest Protect. Not anymore. Google stopped making it in 2025 and named the First Alert SC5 as its official replacement. So here’s what to buy now, based on which smart home setup you already use.

How we picked

We didn’t set fires in a test house. We compared listing and certification details, ecosystem support, power options, and price, and leaned on hands-on reviews from outlets like Reviewed and Tom’s Guide plus long-term owner feedback. Every pick here detects both smoke and carbon monoxide (or, for the renter pick, works with alarms that do).

Quick picks

1. First Alert SC5: best overall, and the Nest Protect replacement

This is the one to get if you use Google Home, and the obvious move if you’re replacing old Nest Protects. Google partnered with First Alert on it and points Nest owners straight to it. Reviews say it fits the Nest mounting bracket and can link with any Nest Protects you still have running, so you don’t have to swap your whole house at once.

It comes in battery and hardwired versions and costs about what the Nest Protect did, around $130. Tom’s Guide’s take is fair: it’s not quite as polished as the Nest was, but it does nearly everything the Nest did, and it’s the best choice for a Google home. Check the First Alert SC5 on Amazon.

2. Kidde Smart Smoke + CO: best for Ring and Alexa homes

If you’ve got Ring cameras or a Ring Alarm system, the Kidde Smart Smoke and CO alarm slides right into that setup, with alerts through the Ring app. It’s a hardwired alarm with battery backup, which makes it an easy upgrade if you already have wired alarms in the ceiling. Reviewed called it one of the smartest alarms they’ve tested, and it usually costs a lot less than the SC5. See the Kidde Smart Smoke + CO alarm.

3. X-Sense Smart Smoke + CO combo: best value for a whole house

The math on smart alarms gets ugly fast when you need one in every bedroom, every hallway, and every level. X-Sense sells multi-packs of battery-powered smoke and CO combo alarms that link to each other wirelessly, so when one goes off, they all go off, and your phone gets the alert. Tom’s Guide picked it as their best value. It’s not tied to Google or Amazon the way the others are, but for covering a big house without rewiring, it’s hard to beat. View X-Sense combo packs.

4. Roost Smart Battery: best for renters

Can’t swap the landlord’s alarms? The Roost is a smart 9V battery. It goes into an existing battery-powered alarm and sends a phone alert when that alarm sounds, plus a heads-up when the battery’s low. No tools, no wiring, no permission needed. It’s not a full smart alarm, and it only works with alarms that take a 9V, but it’s a cheap, clever upgrade. Check the Roost Smart Battery.

What to look for

Smoke and CO in one. Carbon monoxide has no smell and no color. If you have gas appliances, a fireplace, or an attached garage, you need CO detection near sleeping areas. A combo unit covers both on one ceiling spot.

The right listings. Look for UL 217 (smoke) and UL 2034 (carbon monoxide) on the box or listing. Skip anything that doesn’t say.

Battery or hardwired. If there’s already a wired alarm in the ceiling, replace it with a hardwired smart alarm. Same brand usually makes it a simpler swap. If not, sealed 10-year battery models mean no battery changes for the life of the alarm.

Your ecosystem. Google Home points to the SC5. Ring and Alexa point to Kidde. If you don’t care about any of that, X-Sense works on its own app.

And remember, every smoke alarm (smart or not) should be replaced 10 years after its manufacture date, according to the National Fire Protection Association. If an old one’s driving you crazy, here’s why your smoke detector chirps even with a new battery.

FAQ

Is the Nest Protect discontinued?

Yes. Google stopped making the Nest Protect in 2025 and named the First Alert SC5 as its official replacement. Existing Nest Protects keep working, but they still expire 10 years after their manufacture date.

What is the best replacement for Nest Protect?

The First Alert SC5. Google recommends it, and reviews say it fits the Nest mounting bracket and can interconnect with remaining Nest Protects in the Google Home app.

Are smart smoke detectors worth it?

For most homes, yes. Phone alerts mean you know about a fire or CO problem even when you’re away, and you get low-battery warnings before the chirping starts. They’re especially worth it for pet owners, frequent travelers, and anyone with aging parents.

Do smart smoke detectors need Wi-Fi?

They need Wi-Fi to send phone alerts, but the alarm itself still sounds locally if your internet goes down. Some, like X-Sense, use a base station to connect.

Where should I put smoke and CO alarms?

The NFPA recommends smoke alarms inside every bedroom, outside each sleeping area, and on every level of the home, including the basement. Put CO alarms outside sleeping areas and on each level.

Can I install a smart smoke detector myself?

Battery models install with a couple of screws. Swapping a hardwired alarm for another hardwired one is usually simple if the connector matches, but turn off the breaker first. If you’re adding new wiring, call an electrician.

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