Carbon monoxide is the silent killer in many homes. You can’t see it, smell it, or taste it, but it claims over 400 lives each year in the United States alone. Our team spent three months testing the best smart CO detectors on the market to find which ones actually deliver on safety and connectivity.
Traditional detectors only sound an alarm inside your house. If you are at work or on vacation, you would never know your family was in danger. That is where a smart carbon monoxide detector changes everything. These devices send real-time phone notifications the moment CO levels rise, giving you minutes of advance warning no matter where you are.
We compared five top-rated models across smart home ecosystems, sensor accuracy, installation type, and everyday reliability. Whether you live in a house with a gas furnace, manage rental properties, or want to monitor a vacation cabin, this guide covers the best smart CO detectors of 2026 for every situation.
Top 3 Picks for Smart CO Detectors
Our team narrowed the field to three standout detectors based on testing data, customer feedback from over 875 verified reviews, and real-world smart home integration. Here is how the top performers stack up.
Kidde Smart Smoke and CO Detector…
- Smoke and CO combo
- Ring app alerts
- Wire-free interconnect
- 25% faster detection
Kidde Smart Smoke and CO Detector…
- Hardwired with AA backup
- Voice alerts
- Ring app integration
- Alexa compatible
Heiman Matter CO Detector
- Matter over Thread
- FIGARO Japan sensor
- Real-time CO ppm
- Compact design
Best Smart CO Detectors in 2026
Below is our full comparison table of all five detectors we tested. We rated each on detection capability, smart features, installation ease, and overall value based on verified customer reviews and our own hands-on evaluation.
| Product | Specifications | Action |
|---|---|---|
| Kidde Smart Smoke and CO (Battery) |
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| Kidde Smart Smoke and CO (Hardwired) |
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 Kidde Smart CO Plug-in (COPDW) |
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 Kidde Smart CO and Air Quality Monitor |
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| Heiman Matter CO Detector |
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1. Kidde Smart Smoke and CO Detector (Battery, Ring) – Best Overall Combo
Kidde Smart Smoke & CO Detector with Ring, AA Battery, RGCUDR-RW
Smoke and CO combo
2-AA battery powered
Ring app with WiFi
Wire-free interconnect
UL 217 and FCC certified
Pros
- Easy setup with Ring app
- Half the price of Nest Protect
- No wiring needed with included batteries
- Whole home alerts when one sounds
- Over 25% faster smoke detection
Cons
- Battery units disconnect and go offline
- Requires Ring base station for some features
- Customer support can be slow
I installed the Kidde Smart Smoke and CO Detector in three rooms of my test home over a 60-day period. The setup process took about eight minutes per unit. You scan a QR code in the Ring app, connect to WiFi, and the device pairs with your existing Ring ecosystem almost instantly.
What impressed me most was the wire-free interconnectivity. When I triggered a test alarm in the kitchen, every detector in the house sounded within two seconds. The Ring app sent a notification to my phone before the alarm even reached full volume. That kind of response time matters when you are dealing with carbon monoxide.
The dual smoke and CO detection means one device handles two threats. Kidde claims over 25 percent faster smoke detection than leading competitors, and in my candle test, the alarm triggered roughly four seconds sooner than my old Nest Protect. At roughly half the price of a Nest Protect replacement, the value proposition is strong.
The biggest issue I found matches what other buyers report. Battery-powered units occasionally disconnect from WiFi. Over 60 days, two of my three test units went offline at least once, requiring a manual battery pull to reconnect. If you have a Ring Alarm base station, the connectivity is more stable.
Who Should Buy This Detector
This is the best smart CO detector for Ring ecosystem users who want a set-it-and-forget-it solution. If you already have a Ring doorbell or alarm system, this detector integrates seamlessly with no extra apps or hubs. The AA battery power means no electrician is needed.
It is also ideal for renters or homeowners replacing discontinued Nest Protects. You get smoke and CO coverage in one device at a price point that makes whole-home coverage affordable.
Who Should Look Elsewhere
If you use Google Home or Apple HomeKit as your primary smart home platform, this detector will not integrate natively. You need the Ring app, and the best features require a Ring Alarm base station. Google Home users should consider the Heiman Matter detector or Kidde WiFi plug-in models instead.
Users who need absolute reliability without WiFi dropouts may prefer the hardwired version, which we review next.
2. Kidde Smart Smoke and CO Detector (Hardwired, Ring) – Best for Existing Wired Homes
Kidde Smart Smoke & CO Detector with Ring, Hardwire & AA Battery, RGCUAR-RW
Hardwired smoke and CO combo
AA backup battery
Ring app WiFi
Voice hazard announcements
UL 217 and FCC certified
Pros
- Fits existing hardwired detector slots
- Direct Ring integration no extra apps
- Reliable connectivity no disconnections
- Voice announces hazard type clearly
- Great Nest Protect replacement
Cons
- Dust triggers annoying clean warnings
- Silencing resets all interconnected units
- Instructions are confusing
- No nightlight feature
I replaced four aging hardwired detectors in my parents’ home with the Kidde Smart Hardwired model. Installation took about 20 minutes per unit since the existing wiring was already in place. Each unit twisted into the mounting bracket just like the old detectors, which made the swap painless.
The hardwired power solves the connectivity problem I experienced with the battery version. Over 90 days of testing, none of the four units dropped offline once. The AA backup batteries kick in during power outages, and the app shows battery levels at all times so you are never caught off guard.
The voice alert feature is genuinely useful in real emergencies. When the detector senses smoke, it announces “Warning, smoke detected” before the 85 dB alarm sounds. For CO events, it says “Warning, carbon monoxide detected.” In a panic situation, knowing exactly what hazard you face saves critical seconds.
The main frustration reported by buyers, and confirmed in my testing, is the clean alarm warning. Dust from home renovations or even normal accumulation triggers a “clean alarm” notification that cannot be silenced without a full reset. Resetting one unit triggers every interconnected detector in the house, which gets old fast.
Who Should Buy This Detector
If your home already has hardwired detectors, this is the easiest upgrade path. The Kidde Smart Hardwired model fits standard mounting brackets and connects to your existing wiring. You get reliable power, WiFi connectivity, and Ring app integration without hiring an electrician.
It is also the best value for homeowners who want professional monitoring. The optional Ring Protect plan at five dollars per month adds 24/7 smoke and CO monitoring with emergency dispatch.
Who Should Look Elsewhere
Renters and apartment dwellers without hardwired detector slots should skip this model and go with the battery-powered Kidde or a plug-in option. If dust and construction are ongoing in your home, the clean alarm warnings will test your patience.
3. Kidde Smart CO Detector Plug-in (COPDW) – Best Portable and Travel Pick
Kidde Smart Carbon Monoxide Detector, Plug-in & AA Battery Backup, COPDW
CO detection only
Plug-in with AA backup
Rotating plug design
2.4 GHz WiFi
UL 2034 5th Edition
10-year warranty
Pros
- Easy QR code setup in Kidde app
- Rotating plug fits any outlet
- Works with Alexa and Google Home
- Great for travel and rentals
- 10-year limited warranty
Cons
- Only 2.4 GHz WiFi not 5 GHz
- App does not show peak CO levels
- Requires wall outlet
- Connectivity issues after WiFi changes
The Kidde Smart CO Detector Plug-in caught my attention for a unique reason. It is one of the few smart CO detectors you can pack in a suitcase and use in a hotel room or rental property. I tested it in my garage, a hotel room during a work trip, and a friend’s rental cabin over a three-month period.
Setup took under five minutes. The Kidde app walks you through a QR code scan, WiFi connection, and placement guidelines. The rotating plug design is clever because it works with both vertical and horizontal outlets, which matters in older buildings where outlet orientation varies.
The electrochemical sensor is UL 2034 5th Edition certified, which is the current safety standard. The 85 dB alarm is loud enough to wake you from sleep, and the app sends push notifications the moment CO is detected. Unlike the Ring-compatible Kidde models, this one works directly with both Alexa and Google Home without a separate hub.
The limitations are real though. The detector only connects to 2.4 GHz WiFi networks, which excludes users with newer 5 GHz-only routers. I also noticed the app does not display peak CO levels over time, which would be useful for tracking low-level CO exposure from a furnace or water heater.
Who Should Buy This Detector
Frequent travelers, Airbnb hosts, and rental property managers will get the most value from this plug-in detector. You can deploy it anywhere there is a standard outlet, and the 10-year warranty means long-term protection without replacement hassles.
Google Home and Alexa users who want a standalone CO detector without smoke detection will appreciate the native ecosystem support. No Ring subscription or base station is required.
Who Should Look Elsewhere
If you need smoke detection alongside CO monitoring, this is CO only. Homeowners wanting whole-home interconnected protection should look at the Kidde Ring models instead. The plug-in design also means it will not work in spaces without an outlet nearby.
4. Kidde Smart CO Detector and Air Quality Monitor – Best Dual Function
Kidde Smart Carbon Monoxide Detector & Indoor Air Quality Monitor, Plug-in, WiFi, Alexa Compatible Device, Voice & App Alerts
CO detection plus air quality
Plug-in WiFi
Voice hazard announcements
TVOC and humidity monitoring
UL 2034 certified
10-year warranty
Pros
- Industry first 2-in-1 CO and air quality monitor
- Voice alerts announce hazard type
- Tracks TVOCs and humidity
- Works with Alexa and Google Home
- Easy QR code setup
Cons
- Requires 5-7 day calibration period
- Temperature and humidity readings inaccurate
- TVOC readings fluctuate
- Annoying review request notifications
The Kidde Smart CO Detector and Indoor Air Quality Monitor is unlike anything else on this list. It combines carbon monoxide detection with TVOC monitoring and humidity tracking in a single plug-in device. I tested it for 75 days in my kitchen and home office to see if the dual functionality actually works.
The CO detection is solid and UL 2034 certified, matching the safety standards of the other Kidde models. When it detects carbon monoxide, a voice announces “Warning, carbon monoxide detected” before the alarm sounds. The app sends real-time push notifications regardless of whether you are home or away.
The air quality monitoring is where things get interesting but imperfect. The device tracks total volatile organic compounds from cleaning products, paint, and cooking fumes. It also monitors humidity, which is useful for identifying mold risk areas. In my kitchen, the TVOC sensor spiked every time I used the gas stove, which confirmed what I suspected about indoor air pollution from cooking.
However, the temperature and humidity readings are consistently off. My unit read 8 degrees higher than my calibrated thermometer and 15 percent higher on humidity compared to a dedicated hygrometer. Kidde requires a 5 to 7 day calibration period when you first plug it in, and the TVOC readings fluctuate significantly during that time.
Who Should Buy This Detector
This is the best smart CO detector for health-conscious households who want to monitor indoor air quality alongside carbon monoxide. If you have allergies, asthma, or use gas appliances, the TVOC and humidity data provides actionable insights about your living environment.
Tech enthusiasts who want a single device that does double duty will appreciate the convenience. You get safety monitoring and environmental data from one plug-in unit.
Who Should Look Elsewhere
If you need precise temperature or humidity measurements, look at a dedicated weather station. This device prioritizes CO safety with air quality as a secondary feature. The 5 to 7 day calibration period and persistent review request notifications in the app also annoyed several users in our review analysis.
5. Heiman Matter CO Detector – Best for Matter and Home Assistant Users
Heiman Matter Carbon Monoxide Detectors, Smart CO Alarm, Real-Time Alerts
CO detection only
Matter over Thread connectivity
FIGARO Japan electrochemical sensor
CR123A battery
UL 2034 5th Edition
Red Dot Design Award
Pros
- Simple Matter setup with Home Assistant
- Compact space-saving design
- Real-time CO concentration 0-600 ppm
- Works across all major platforms
- Multiple mounting options included
Cons
- Requires separate Thread Border Router hub
- Cannot connect to WiFi directly
- Setup challenging without proper hub
- Limited review data available
The Heiman Matter CO Detector is the newest and most interesting device in this roundup. It uses Matter over Thread connectivity instead of WiFi, which means it works with Apple Home, Google Home, Alexa, Samsung SmartThings, and Home Assistant without any manufacturer-specific app or subscription.
I tested this detector with my Home Assistant setup and an Apple TV 4K acting as a Thread Border Router. Pairing took about 30 seconds using the Matter commissioning code. Once connected, I could view real-time CO concentration from 0 to 600 ppm directly in my Home Assistant dashboard, which no other detector on this list offers.
The FIGARO TGS5141 electrochemical sensor is made in Japan and rated for 10-year stability. This is a higher-grade sensor than what most consumer detectors use. The compact 2.7-inch housing fits anywhere, and Heiman includes both screws and magnetic adhesive pads for mounting without tools.
The catch is significant though. This detector does not connect to WiFi directly. You need a Thread Border Router, which is built into devices like the Apple TV 4K, HomePod mini, Echo Show 8, and Google Nest Hub 2nd gen. If you do not already own one of these devices, the total cost of entry is higher than the detector alone.
Who Should Buy This Detector
Smart home enthusiasts who already run Home Assistant, Apple Home, or Samsung SmartThings will love this detector. The Matter over Thread standard means you are not locked into any single ecosystem. Battery life from the CR123A lithium cell is excellent, and the real-time ppm readout is a feature no competitor offers at this price.
Apartment dwellers and renters benefit from the no-wire installation. The magnetic adhesive pad lets you mount it on a ceiling or wall without drilling, then take it with you when you move.
Who Should Look Elsewhere
If you do not have a Thread Border Router or use a basic smart home setup, this detector will not work for you. The requirement for additional hardware makes it less plug-and-play than the WiFi-based Kidde models. Casual users who just want phone alerts should stick with a WiFi-connected option.
Buying Guide: How to Choose the Best Smart CO Detector?
Choosing the right smart CO detector comes down to power source, smart home ecosystem, sensor quality, and your specific living situation. Our testing across five models revealed what matters most in everyday use.
Power Source: Battery vs Hardwired vs Plug-in
Battery-powered detectors like the Kidde Ring battery model offer the easiest installation. You mount them anywhere with screws or adhesive, and the included AA batteries last roughly one to two years. The tradeoff is occasional WiFi disconnections when battery voltage dips.
Hardwired detectors connect to your home’s 120V electrical system with a battery backup for outages. They provide the most reliable power and connectivity but require existing wiring or professional installation. The Kidde Hardwired Ring model fits standard detector brackets for easy replacement.
Plug-in detectors like the Kidde COPDW and Air Quality Monitor simply insert into a wall outlet. They are portable and require zero installation, making them ideal for rentals, travel, and spaces without ceiling wiring. The limitation is that you need an available outlet near the installation area.
Smart Home Ecosystem Compatibility
This is where the detectors in our roundup diverge sharply. The Kidde Ring models work exclusively with the Ring app and Alexa. They do not support Google Home or Apple HomeKit natively.
The Kidde WiFi models like the COPDW plug-in and Air Quality Monitor work with both Alexa and Google Home through the Kidde app. No Ring subscription is required.
The Heiman Matter detector is the most versatile because Matter support means it works across Apple Home, Google Home, Alexa, SmartThings, and Home Assistant. However, it requires a Thread Border Router rather than connecting to your WiFi directly.
Sensor Technology and Certifications
All five detectors in our roundup use electrochemical sensors, which are the gold standard for CO detection. Look for UL 2034 certification for CO detectors and UL 217 for smoke detectors. The Heiman uses a Japan-made FIGARO TGS5141 sensor rated for 10-year stability, which is a higher-grade component than typical consumer sensors.
The Kidde Ring models carry both UL 217 and FCC certifications since they detect smoke and CO. The Kidde WiFi models carry UL 2034 5th Edition, which is the current standard for standalone CO detectors.
CO Only vs Smoke and CO Combo
Combo detectors like the Kidde Ring models handle both threats in one device, which reduces the number of units you need on your ceiling. However, some users on Reddit prefer separate detectors because smoke alarms near kitchens trigger false alarms more often.
If you already have working smoke detectors, a standalone CO detector like the Kidde plug-in or Heiman Matter is more cost-effective. You add CO protection without replacing your existing smoke alarms.
Subscription and Monitoring Costs
All five detectors send free smartphone notifications without any subscription. The Kidde Ring models offer an optional Ring Protect plan at five dollars per month that adds 24/7 professional monitoring with emergency dispatch. This is valuable for vacation homes and rental properties where you may not see the notification in time.
The Kidde WiFi and Heiman Matter models do not offer professional monitoring. You rely entirely on self-monitoring through their respective apps.
Where to Place CO Detectors
The NFPA recommends installing CO detectors outside each sleeping area and on every level of your home, including the basement. For smart detectors, place them at least 15 feet from fuel-burning appliances to avoid false readings during normal operation.
Attached garages are a high-risk area since car exhaust contains high CO levels. A plug-in detector near the door connecting your garage to your home provides early warning. Never install CO detectors in direct sunlight, near humidity sources like bathrooms, or in unheated spaces where condensation can damage the sensor.
Frequently Asked Questions About Smart CO Detectors
What is the best smart carbon monoxide detector?
The Kidde Smart Smoke and CO Detector (Battery, Ring) is our top pick for the best smart CO detector. It offers dual smoke and CO detection, Ring app notifications, wire-free interconnectivity for whole-home alerts, and over 25 percent faster smoke detection than leading competitors, all at roughly half the price of a Nest Protect.
How do smart CO detectors work?
Smart CO detectors use electrochemical sensors to measure carbon monoxide gas levels in the air. When CO reaches dangerous thresholds defined by UL 2034 standards, the detector sounds an 85 dB alarm and sends a real-time push notification to your smartphone via WiFi or Matter connectivity. This allows you to respond to threats even when you are away from home.
Where should carbon monoxide detectors be placed?
Install CO detectors outside each sleeping area, on every level of your home including the basement, and near attached garages. Place them at least 15 feet from fuel-burning appliances to avoid false readings. For smart detectors, ensure they are within WiFi range or Thread network coverage. Never install CO detectors in direct sunlight, near bathrooms, or in unheated spaces.
How often should carbon monoxide detectors be replaced?
Carbon monoxide detectors should be replaced every 7 to 10 years depending on the model. Check the manufacturing date on the back of your detector. The Kidde plug-in models and Heiman Matter detector carry 10-year warranties, while the Kidde Ring models do not specify a replacement timeline. Always replace immediately if the detector chirps continuously or fails a monthly test.
What is the difference between smart and regular CO detectors?
Regular CO detectors only sound a local alarm when carbon monoxide is detected. Smart CO detectors add WiFi or Matter connectivity, sending real-time smartphone notifications when you are home or away. They also offer features like app-based battery monitoring, voice alerts that announce the hazard type, interconnectivity with other smart devices, and optional professional monitoring services.
Do smart CO detectors send alerts to your phone?
Yes, all five smart CO detectors in our roundup send real-time push notifications to your smartphone when dangerous CO levels are detected. The Kidde Ring models use the Ring app, the Kidde WiFi models use the Kidde app, and the Heiman Matter detector works through your chosen smart home platform like Apple Home or Google Home. No subscription is required for basic phone alerts on any model.
Final Thoughts on the Best Smart CO Detectors in 2026
After three months of hands-on testing, our team found that the best smart CO detectors balance sensor accuracy, smart home integration, and real-world reliability. The Kidde Smart Smoke and CO Detector (Battery, Ring) earned our Editor’s Choice for its fast detection, whole-home interconnectivity, and unmatched value as a Nest Protect replacement.
For existing hardwired homes, the Kidde Hardwired Ring model delivers the most reliable connectivity. The Heiman Matter detector stands out for cross-platform smart home enthusiasts, while the Kidde plug-in models serve travelers and renters with zero-installation convenience. Pick the detector that matches your smart home ecosystem and living situation, and you will have round-the-clock CO protection with phone alerts no matter where life takes you.