Best Smart Smoke and Carbon Monoxide Detector (2026)
Last updated: November 8, 2026
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A regular smoke alarm only helps if someone is home to hear it. A smart smoke and carbon monoxide detector sends an alert to your phone when it detects smoke or CO. You can call for help or check on family, even from work or on vacation.
With Google’s Nest Protect discontinued, many people need a replacement. We compared current smart smoke and CO alarms on sensors, power, alerts and smart home support. Here are our picks.
Our top picks
| Alarm | Power | Score | Buy link |
|---|---|---|---|
| First Alert SC5 Smart Smoke and CO AlarmBest overall | Battery or hardwired | 9 | Check price |
| Kidde Smoke + CO Alarm with Smart FeaturesBest for existing Kidde wiring | Hardwired (120V) | 8.8 | Check price |
| X-Sense SC07-WX Smart Smoke and CO AlarmBest budget smoke + CO | Replaceable battery | 8.5 | Check price |
| Kidde Battery Smart Smoke and CO Alarm (Ring)Best for Ring users | Replaceable AA batteries | 8.4 | Check price |
| X-Sense XS01-WX Wi-Fi Smoke AlarmCheapest smart smoke alarm | Replaceable battery (smoke only) | 8.1 | Check price |
The best smart smoke and carbon monoxide detectors, reviewed
First Alert SC5 Smart Smoke and CO Alarm
- SensorsPhotoelectric smoke and electrochemical CO
- Power6 CR123A batteries, or hardwired with battery backup
- AppResideo Connect app
- AlertsPhone alerts, voice alerts with Heads-Up warning
- Price$129.99 at First Alert
First Alert says the SC5 works with and replaces Google’s Nest Protect. It can also use the same mounting bracket, so swapping is simple.
It detects smoke and carbon monoxide and sends phone alerts through the Resideo Connect app. Its voice alerts with a Heads-Up warning tell you the type and location of the danger.
You can test it from the app. Compatible alarms interconnect, so when one sounds, they all sound. The battery and hardwired versions both cost $129.99 at First Alert, and it has a 10-year limited warranty.
What we like
- Works with and replaces Nest Protect
- Smoke and CO in one alarm
- Voice alerts say type and location of danger
- Battery or hardwired versions
Watch out for
- Highest price on this list
- Battery version uses six CR123A batteries
- Needs the Resideo Connect app
Best for: Former Nest Protect owners and anyone who wants voice alerts.
Skip it if: You want the lowest-cost smart alarm.
Check price on Amazon Price range:
Kidde Smoke + CO Alarm with Smart Features
- ModelP4010ACSCO-WF
- SensorsSmoke and CO
- PowerHardwired
- AppKidde app over Wi-Fi
- PriceSee retailers
If your home already has Kidde hardwired alarms, this is an easy upgrade. It is designed to work with your existing Kidde hardwire interconnected alarms.
When any of those alarms goes off, even one without smart features, they all sound and you get an alert on your phone. That means one smart unit can bring phone alerts to the whole set.
The Kidde app lets you test the alarm and tells you when it needs replacing. Smart Hush lets you silence a false alarm from the app when your phone is on the same Wi-Fi. Setup is done by scanning the QR code, and it has a 10-year limited warranty.
What we like
- Adds phone alerts to existing Kidde wiring
- Smart Hush from the app
- Test from the app
- 10-year limited warranty
Watch out for
- Needs existing alarm wiring
- Smart Hush only works on your home Wi-Fi
- Price not listed on Kidde’s site
Best for: Homes with Kidde hardwired smoke alarms.
Skip it if: You have no alarm wiring.
Check price on Amazon Price range:
X-Sense SC07-WX Smart Smoke and CO Alarm
- SensorsPhotoelectric smoke and electrochemical CO
- PowerReplaceable CR123A battery (about 1 year)
- Connectivity2.4 GHz Wi-Fi, no base station
- DisplayLCD with CO level
- Price$36.54 (1-pack) at X-Sense
The SC07-WX is the lowest-cost way on this list to get smoke and CO alerts on your phone. It connects straight to your 2.4 GHz Wi-Fi, so you don’t need a hub or wiring.
The screen shows the CO level, and the X-Sense Home Security app shows it too. You can share the alarm with up to 12 family members in the app.
The battery is replaceable and X-Sense says it usually lasts about a year. The alarm itself lasts up to 10 years. These alarms do not sound together, so each one only warns its own room.
What we like
- Low price for smoke and CO
- No hub or wiring needed
- LCD shows CO level
- App sharing with family
Watch out for
- Battery needs changing about once a year
- Alarms do not interconnect
- 2.4 GHz Wi-Fi only
Best for: Renters and budget buyers who want smoke and CO alerts without wiring.
Skip it if: You need every alarm to sound together.
Check price on Amazon Price range:
Kidde Battery Smart Smoke and CO Alarm (Ring)
- SensorsPhotoelectric smoke and electrochemical CO
- Power2 replaceable AA batteries
- Connectivity2.4 GHz Wi-Fi, Ring app
- Alarm85 dB at 10 ft, voice alerts
- Price$69.98 at Ring
Ring and Kidde made this battery smoke and CO alarm together. It connects to 2.4 GHz Wi-Fi and sends smoke, CO and low-battery alerts to the Ring app, with no subscription and no extra Ring devices needed.
Ring says its smoke sensing is over 25% faster and that it gives early warnings at low CO levels. It also has voice alerts and an 85 dB siren.
It runs on two AA batteries, so there is no wiring. It also links wire-free with compatible Kidde alarms, so when one sounds, they all sound. Optional 24/7 smoke and CO monitoring costs $5 a month.
What we like
- Alerts in the Ring app, no subscription
- Smoke and CO in one alarm
- No wiring needed
- 10-year limited warranty
Watch out for
- Best fit for Ring app users
- Batteries need changing
- 2.4 GHz Wi-Fi only
Best for: Ring users who want smoke and CO alerts without wiring.
Skip it if: You do not use the Ring app.
Check price on Amazon Price range:
X-Sense XS01-WX Wi-Fi Smoke Alarm
- SensorsPhotoelectric smoke only, no CO
- PowerReplaceable CR123A battery (about 1 year)
- Connectivity2.4 GHz Wi-Fi, X-Sense Home Security app
- Base stationNot needed (not compatible with SBS50)
- Price$29.99 (1-pack) at X-Sense
The XS01-WX is the cheapest way here to get smoke alerts on your phone. It connects directly to 2.4 GHz Wi-Fi.
You can silence it from the app, so no ladder is needed for a false alarm. It checks its own battery and sensor and warns you when the battery is low.
It detects smoke only, not carbon monoxide. Pair it with a CO alarm on each level if you have gas appliances, a fireplace or an attached garage.
What we like
- Very low price
- Silence from the app
- Phone alerts without a hub
- Small and easy to install
Watch out for
- Does not detect carbon monoxide
- Battery needs changing about once a year
- Alarms do not interconnect
Best for: Budget buyers adding smart smoke alerts to bedrooms and hallways.
Skip it if: You need CO detection in the same device.
Check price on Amazon Price range:
Side-by-side comparison
| First Alert SC5 Smart Smoke and CO Alarm | Kidde Smoke + CO Alarm with Smart Features | X-Sense SC07-WX Smart Smoke and CO Alarm | Kidde Battery Smart Smoke and CO Alarm (Ring) | X-Sense XS01-WX Wi-Fi Smoke Alarm | |
|---|---|---|---|---|---|
| Best for | Best overall | Best for existing Kidde wiring | Best budget smoke + CO | Best for Ring users | Cheapest smart smoke alarm |
| Smoke detection | Yes | Yes | Yes | Yes | Yes |
| CO detection | Yes | Yes | Yes | Yes | No |
| Power | Battery or hardwired | Hardwired | Replaceable battery | AA batteries | Replaceable battery |
| Works with | Resideo Connect | Kidde app | X-Sense app | Ring app | X-Sense app |
| Alarms sound together | Yes | Yes (Kidde hardwired) | No | Yes (compatible Kidde) | No |
| Hub needed | No | No | No | No | No |
| Official price | $129.99 | Not listed | $36.54 | $69.98 | $29.99 |
| Price | |||||
| Our score | 9 | 8.8 | 8.5 | 8.4 | 8.1 |
What happened to Nest Protect?
Google discontinued the Nest Protect. First Alert says its SC5 is compatible with and replaces the Nest Protect, and it can use the same mounting bracket.
Your Nest Protect keeps working until it expires. Every smoke alarm should be replaced about 10 years after it was made, so check the date on the back.
Where to install smoke and CO alarms
- Inside every bedroom and outside each sleeping area.
- On every level of the home, including the basement.
- CO alarms near sleeping areas and on each level if you have gas appliances, a fireplace or an attached garage.
- Away from kitchens and bathrooms by about 10 feet to reduce false alarms from cooking and steam.
- On the ceiling or high on the wall, following the manufacturer’s instructions.
The US Fire Administration and NFPA recommend testing alarms monthly and replacing smoke alarms every 10 years. Check your local code for requirements in your area.
How to choose a smart smoke and CO detector
1. Get both smoke and CO protection
Carbon monoxide is invisible and odorless. Combination alarms cover both dangers in one device, which is simpler for most homes.
2. Match your wiring
If you already have hardwired alarms, pick a hardwired smart model from the same brand so it links with them. Otherwise, battery models install anywhere.
3. Pick your smart home platform
The First Alert SC5 uses the Resideo Connect app. The Kidde smart alarm uses the Kidde app, and the Kidde Battery Smart alarm uses the Ring app. X-Sense alarms use their own app.
4. Look for interconnection
Interconnected alarms all sound when one detects danger, so you hear a basement fire from an upstairs bedroom. Not every smart alarm does this, so check before you buy.
5. Check the battery type
Sealed 10-year batteries mean no battery changes. Replaceable batteries cost less up front but need changing, often about once a year.
Frequently asked questions
Are smart smoke detectors worth it?
For most homes, yes. Phone alerts let you respond to fire and carbon monoxide even when you are away.
What is the best replacement for Nest Protect?
The First Alert SC5 Smart Smoke and CO Alarm. First Alert says it works with and replaces Nest Protect, and it comes in battery and hardwired versions.
Do smart smoke detectors work without Wi-Fi?
Yes. The alarm still sounds locally if it detects smoke or CO. You only lose phone alerts until Wi-Fi returns.
How often should I replace smoke and CO alarms?
Replace smoke alarms about every 10 years. Follow the maker’s replacement date for CO alarms, printed on the back.
Can I mix smart and regular smoke alarms?
Often, yes. A hardwired smart alarm can link with compatible hardwired alarms from the same brand, so every alarm sounds and you still get phone alerts.
Where should carbon monoxide detectors go?
Place CO alarms outside sleeping areas and on every level of the home, especially if you have fuel-burning appliances, a fireplace or an attached garage.
The bottom line
For most homes, the First Alert SC5 is the best smart smoke and carbon monoxide detector and a direct Nest Protect replacement.
Choose the Kidde smart alarm to upgrade Kidde hardwired alarms. Pick the X-Sense SC07-WX for budget smoke and CO alerts, or the Kidde Battery Smart alarm for Ring. The X-Sense XS01-WX is the cheapest smoke-only option.
Prepare for other emergencies too: see the best water leak detectors with phone alerts, browse all Fire, Water & Emergency guides, or ask us a question.
Sources
- First Alert: SC5 Battery Smart Smoke and CO Alarm
- First Alert: SC5 Hardwire Smart Smoke and CO Alarm
- Kidde: Smoke + CO Alarm with smart features
- X-Sense: SC07-WX Smart Smoke and CO Alarm
- Ring: Kidde Battery Smart Smoke and CO Alarm
- X-Sense: XS01-WX Wi-Fi Smoke Alarm
Product images: First Alert, Kidde, Ring and X-Sense official sites. Featured photo: ‘Smoke Detector’ by HomeSpot HQ, licensed under CC BY 2.0.
