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The Best Carbon Monoxide (CO) Detectors of 2020

From smart carbon monoxide detectors to simple plug-in units, we found the best CO detectors available to keep your home and family safe.
Written by | Updated October 19, 2020
Best overall
nest protect productGoogle Nest Protect
  • Compatible with Nest Secure system
  • Senses carbon monoxide, heat, and smoke
  • Compatible with Nest Secure system
  • Senses carbon monoxide, heat, and smoke
Best voice control
First Alert Carbon Monoxide DetectorFirst Alert OneLink
  • Works with Amazon Alexa
  • Voice alarm option
  • Works with Amazon Alexa
  • Voice alarm option
Budget pick
Alert Plus CO detectorAlert Plus Carbon Monoxide Detector
  • Voice or siren alerts
  • Digital display
  • Batteries included
  • Voice or siren alerts
  • Digital display
  • Batteries included

Bottom line: Google Nest Protect is anything but basic

Nest Protect marries safety features like smoke, fire, and carbon monoxide detection with intuitive smart features. It’s also a companion to your home security system and even a nightlight. 

It comes with an option for voice alerts to minimize panic. And it connects to the Nest app, so you’ll get alerts from anywhere.

Learn more in our full review of Nest Protect, or read on to compare this top carbon monoxide detector to our other favorites.

Top 5 carbon monoxide detectors

Compare CO detectors and alarms

After hours of research and testing, we’ve found the best carbon monoxide detectors available. From basic battery operated to smart devices, you can find the top options here.

List price
Smart features
Digital display
Smoke sensor
Best overall
Best voice control
Budget pick
Best value
Easy installation
Nest Protect First Alert OneLink Alert Plus Carbon Monoxide Detector Kidde Battery-Operated Kidde Nighthawk Plug in
nest protect product First-Alert-Carbon-Monoxide-Detector Alert Plus CO detector Kidde Battery Powered CO Detector kidde nighthawk plugin_product image
$119.00 $202.83 $18.48 $21.47 $28.03
View on Home Depot View on Amazon View on Amazon View on Amazon View on Amazon

*Amazon.com prices as of 10/19/20 01:23 pm MST. See full disclaimer.

Our approach

To find the best carbon monoxide detectors, we compared smart features, installation ease, and detection accuracy. We also looked at user reviews to get a better idea of how these devices work first hand. Visit our methodology page to learn more about how we conduct reviews like this one.

CO detector and alarm reviews

1. Google Nest Protect: Best carbon monoxide detector

Best Overall
nest protect product

Nest Protect combines smoke and carbon monoxide detection and works with an app. When you download it, you can get alerts to your phone and even silence alarms if necessary. With state-of-the-art sensors for both fire and carbon monoxide, this alarm is one of the best for homeowners or renters.


  • Works with other smart home devices
  • Doubles as smoke detector
  • Comes with battery or hardwire capabilities
  • Features voice notifications


  • When the battery dies, you'll need a new alarm

You can’t change the batteries in this unit, so you’ll need to replace the whole thing once it expires. Even at $120, Nest Protect is still a good value if it lasts for its full life expectancy of 10 years.

Learn more about the Nest Protect in our full product review.

Best Voice Control
First Alert Carbon Monoxide Detector

The Onelink smart smoke and carbon monoxide detector can do a lot. Using your home’s Wi-Fi, the alarms can talk to one another and synchronize to alert you if there is a gas leak or fire. You can also control it from your Apple device through an app, so you can silence the alarm or get notifications on your phone.


  • 10-year battery
  • Mobile app
  • Voice alarm
  • Syncing system
  • Built-in smoke alarm


  • Big price tag
  • When the battery dies, you'll need a new alarm

Onelink doesn’t have a battery compartment that you can access, so when it dies you’ll need to get a new CO detector. With a price tag over $200, that steep replacement cost might be more than some want to pay.

3. Alert Plus Carbon Monoxide Detector: Budget pick

Budget pick
Alert Plus CO detector

The Alert Plus Carbon Monoxide Detector is a simple device with one job—to keep you and your family safe from CO poisoning. Unlike our top picks, it only detects carbon monoxide and shows levels on an easy-to-read LED screen.

And while it doesn’t have any smart features, it does have a voice option that speaks to you when there’s danger. Some might find this less stressful than a loud alarm. But if you prefer the traditional siren, it has a powerful 85 dB siren to warn everyone in your home.


  • Affordable
  • Batteries included
  • Voice or siren alerts


  • No smart features

It’s also one of the easiest devices to install. Just mount the backplate to the wall, add the batteries (included with the unit), and click the monitor into place.

And for under $20, you can afford to add more than one to your home. Place your Alert Plus CO detector in the basement, kitchen, garage, or anywhere you burn fossil fuels. We even saw reviews from users who kept it in their vehicle.

4. Kidde Battery-Operated: Best value

Best value

The Kidde Battery Operated CO detector checks the air every 15 seconds for continuous monitoring with its electrochemical sensor. It doesn’t rely on hardwiring either, so it will continue to work even during a power outage. To top it off, it has a powerful 85 dB siren that sounds when it senses the poisonous gas.


  • No drilling required
  • Test button
  • Signature beep


  • No home automation
  • No smoke detection
  • No battery backup

While it lacks the smart features seen in the Nest and OneLink carbon monoxide detectors, it has all the marks of a reliable device. In addition to its loud siren and consistent monitoring, it has a green and red light to give visual safety cues to people with hearing loss.

If you need multiple CO detectors, this is a good device to start with. It’s affordable, dependable, and easy to install.

5. Kidde Nighthawk Plug-in: Easy installation

Best Value
kidde nighthawk plugin_product image

When we say installing the Kidde Nighthawk carbon monoxide detector is easy, we mean it. You won’t need drills, screws, or even batteries. Just plug it in, and it’s all set. It also comes with a 9-volt backup battery in case of a power outage.


  • Affordable price
  • Digital display
  • Positive customer reviews
  • Backup battery


  • Not compatible with home automation
  • Hardwired only

Plug-in options like this CO detector keep renters and landlords happy. No need to drill holes in the wall.

Like other carbon monoxide detectors, it comes with a test button and LED screen to show the CO levels in your home. When the Nighthawk detects dangerous levels in your home, it will emit a signature beeping pattern so you won’t confuse it with any other alarms in your home.

How do carbon monoxide detectors work for people with hearing loss?

Loud sirens are the standard for carbon monoxide detectors, but what if someone in your family has hearing loss? We found wire-in units that connect to smoke and carbon monoxide detectors that trigger a strobe light when there's an emergency.

Types of carbon monoxide detectors

There are several types of carbon monoxide detectors available for purchase. Some include multiple functions:

  • Dual-function: sense different threats like CO, smoke, and fire
  • Digital: show you levels of carbon monoxide on a digital screen
  • Smart: run diagnostics and sync with home automation apps
  • Hardwired: wire into your home’s electrical grid, work unless the power goes out
  • Battery-operated: basic sensing and display, need batteries to operate

Carbon monoxide detectors FAQ

Check out our full frequently asked questions page to learn more about carbon monoxide detectors.

What are the symptoms of carbon monoxide poisoning?

CO poisoning creates flu-like symptoms like dizziness, nausea, vomiting, headaches, confusion, or fainting.

What should I do if I get CO poisoning?

If you’re at home, get out of the house and call 911. CO poisoning doesn’t always hit suddenly and doesn’t leave your system quickly, so it’s a good idea to seek medical attention as soon as you can.

How common is CO poisoning?

Every year, 400 Americans die from accidental carbon monoxide poisoning and 20,000 are admitted to the emergency room.

Who is most susceptible to CO poisoning?

Everyone is susceptible to carbon monoxide poisoning, but children, older adults, people who are physically ill, and pets are more likely to be affected by CO.

How do carbon monoxide detectors work?

Carbon monoxide detectors work like smoke detectors but detect levels of carbon monoxide instead.

CO detectors usually have one or more of these sensors:

  • Biomimetic detectors use color-changing gels that absorb carbon monoxide which triggers the alarm.
  • Metal oxide semiconductors have silica chips that detect CO and send electrical signals to trigger an alarm.
  • Electrochemical sensors use electrodes in chemical solutions that sense changes in electrical currents when carbon monoxide is present, and they sound an alarm.

Most professionally monitored security systems come with a CO detector. Check out our top security providers to see which home security systems include CO detectors with their monitoring plans.

Where should I install carbon monoxide detectors?

Put a carbon monoxide detector outside every separate sleeping area in your home, your kitchen, basement, and garage. We recommend finding an area far enough from the carbon monoxide source but close enough to the areas you and your family normally occupy.

Check out our full guide on where to install your own carbon monoxide detectors.

CO detector maintenance

Most carbon monoxide detectors last an average of five years. Although the product’s lifetime will vary depending on your make and model, you can still get the most out of your detector by wiping it down weekly to keep it clean from dust and debris.

Just like your smoke detectors, it’s a good idea to test your CO detector monthly. Start by pressing the “test” button to ensure the siren works. If your detector is older, you can purchase a carbon monoxide meter to find out if your detector is still fully functional. If the carbon monoxide sensor doesn’t go off when you test it, it’s probably time to buy a new one.

Sources of carbon monoxide gas


Carbon monoxide (CO) has been called the “silent and invisible killer” because it doesn’t have a smell, color, or taste. It’s one of the most prevalent causes of death due to poisoning in America. Any time you burn something—like gasoline, natural gas, wood, oil, propane, or charcoal—carbon monoxide is released into the air.

In outdoor spaces, this usually isn’t a health hazard because there is enough area for the CO to dissipate, so particles never amount to a toxic level. The danger comes when carbon monoxide is released in a contained area like your home, RV, or garage.

Anything that burns will create carbon monoxide. It’s not just your stove, fireplace, or grill either. Here are some of the things that can create carbon monoxide when turned on:

  • Appliances
  • Gas grills
  • Gas stoves
  • Gas or oil-burning furnaces
  • Fuel-burning water heaters
  • Non-electric space heaters
  • Tools
  • Snowblowers
  • Lawnmowers
  • Pressure washers
  • Generators
  • Non-electric cars, trucks, and boats
  • Chain saws

Know what to do and what not to do

Lighting a fire in your fireplace is okay if it’s properly ventilated. However, if you do the following, you could cause dangerous levels of carbon monoxide to build in your home.


  • Always vent gas appliances properly
  • Get your chimney checked annually to ensure proper ventilation

fireplace illustration


  • Never burn gas grills inside your home
  • Don’t use your gas stove/oven for heating
  • Don’t leave the car running with the garage door closed
  • Don’t patch or seal vent pipes with tape or unapproved products or carbon monoxide could leak into your home
  • Don’t ever burn charcoal inside
  • Never run a generator in your home or within 20 feet of your home’s doors, windows, and garage
  • Don’t turn on your car if the tailpipe is blocked (by snow or anything else)


*Amazon.com list price as of 10/19/20 01:23 MST. Product prices and availability are accurate as of this date/time indicated and are subject to change. Any prices and availability information displayed on Amazon at the time of purchase will apply to the purchase of this product. Safewise.com utilizes paid Amazon links.

Certain content that appears on this site comes from Amazon. This content is provided “as is” and is subject to change or removal at any time.

Written by Katie McEntire

Katie McEntire has tested home security systems in her own apartment, installed GPS trackers in her own car, and watched her cat, Toki, nap all day through a live nanny cam feed. As an expert reviewer, she believes that firsthand experience is the best way to learn about new products (even if it requires being the guinea pig). She specializes in pet safety and DIY security and has contributed to publications like DigitalCare.org and TechGuySmartBuy. Learn more

Share this article.
  • http://www.reviews.org Scott T.

    What do you think of our picks for best carbon monoxide detectors and alarms? Is there something we missed, or what else would you like to know?

    • PLK

      How many different units were tested? Are the results based on testing, i.e. using the UL standard or just the features offered?

  • joeandmilly

    Nest is compatible with both Android and Apple, not sure why she wrote only compatible with Apple. nest is owned by Google, which produces the Android OS along with Google Home

    also First Alert is compatible with both iOS and Android as well.

    • http://www.reviews.org Scott T.

      Nice catch! We try to keep things updated, but sometimes tech moves faster than we do. We’ll update it!

  • Sumit

    Check: The Home Security Solution Blog

  • Sumit

    to know more about the digital home security solution check: The Home Security Solution Blog

  • http://gspirits.com/ Zod

    I purchased the FirstAlert C0400 for use in my basement that has a gas fired furnace and water heater. I liked that it was small and simple. After about 2 weeks of use, the thing started giving a low battery chirp.. ok, just swap out the battery! 2 weeks later, I’m getting a low battery chirp again. What? I out in a fresh Duracell! Popped out the battery and tested the voltage with my Fluke meter….7.75 volts. I still had the old battery. I tested that. 7.75 volts. My conclusion is that this thing eats batteries! At one battery every 2 weeks, that 26 batteries a year…at $3/battery, that’s $78 a year..plus the hassle of popping the batteries in and out! No! This is not a good thing! That plug-in Kidde for $30 looks to be the better value just because it is plug-in!

    • Rebecca Edwards

      Thank you so much for sharing your experience. We will add your notes to our testing and customer experience database and check for this phenomenon when we re-test and re-evaluate our rankings. Your input is valuable and so helpful to others looking to make the best choice for a CO detector in their home. Thanks, again!

    • Rebecca Edwards

      Thanks again for sharing this information. We looked into this and found that others are having the same problem. It looks like the manufacturing date might be the problem. Many have gotten units that were manufactured 10 years ago, which means the product is likely expired. We’re so sorry this happened, and we’ll add an update to our page to let others know.

  • homenow.io

    Kidde consistently makes great products!