Best Carbon Monoxide (CO) Detectors

You need a carbon monoxide detector to protect against accidental poisoning; here are our suggestions

Best Traditional
Kidde KN-COPP-3
Kidde KN-COPP-3
4 out of 5 stars
4
$29.22
  • Check
    Excellent reputation
  • X
    Plug-in only
Best Combo
Kidde KN-COSM-BA
Kidde KN-COSM-BA
4.5 out of 5 stars
4.5
Starting from
$44.99
  • Check
    Voice warnings
  • X
    No digital display
Best for Google
Nest Protect
4 out of 5 stars
4
$114.80
  • Check
    Google Assistant compatibility
  • X
    No digital display
Best for Alexa
Onelink Safe & Sound
Onelink Safe & Sound
3.5 out of 5 stars
3.5
$264.99
  • Check
    Built-in Alexa speaker
  • X
    Expensive
Budget Pick
Kidde KN-COB-LP2 9CO5-LP2
Kidde KN-COB-LP2 9CO5-LP2
4.3 out of 5 stars
4.25
$23.99
  • Check
    Affordable
  • X
    No smoke alarm
Brianne Sandorf
Staff Writer, Home Security & Smart Home
Read More
December 01, 2021
8 min read

Whether you want the cheapest option or the finest technological advancements, we’ve got a CO detector recommendation.

Our top pick for CO detection is a more traditional Kidde alarm. We’ve also got the ultra-smart Google Nest Protect smoke and carbon monoxide detector and the Alexa-compatible Onelink Safe & Sound, among other recommendations.

Let’s jump into our list of the best carbon monoxide detectors.

How we chose
Info Box

We looked at nearly 40 different carbon monoxide detectors and winnowed it down to five top choices.

Compare best carbon monoxide detectors
Name
Price
Power source
Smoke alarm
See details
$29.22

Plug

Icon No  DarkNo
$44.99

Battery

Icon Yes  DarkYes
$114.80

Battery or wired

Icon Yes  DarkYes
$264.99

Plug

Icon Yes  DarkYes

$23.99

Battery

Icon No  DarkNo

Amazon.com List Prices (as of 11/23/2021 11:05 MST). Offers subject to change.

What to look for in a carbon monoxide detector

In the US, at least 450 people die of carbon monoxide (CO) poisoning each year. Another 50,000 wind up in the emergency room because they’ve inhaled the odorless but deadly gas.¹ You can keep yourself from being one of these numbers by installing a carbon monoxide detector.

Carbon monoxide detector features:

  • Smoke alarms
  • Voice alarms
  • Battery options
  • Digital displays
  • Smart home compatibility
  • Accessible false alarm buttons

You’ll notice that our recommendation for the best carbon monoxide detector doesn’t have most of these features. CO detectors are one of the few home safety items where we don’t see a huge need for super smarts. A garden variety CO detector should do a fine job. But just in case, we’ve included a range of functionality in recommendations.

Want to read more?

Kidde Nighthawk KN-COPP-3 Carbon Monoxide Alarm Detector: Best traditional option

4 out of 5 stars
4
Pro Bullet Excellent reputation
Pro Bullet Digital display
Pro Bullet Six-foot cord

The Kidde KN-COPP-3 is the best conventional carbon monoxide sensor. It’s plain, but it does what needs to be done.

We picked this Kidde detector largely because of its reputation. This device may be old school, but it’s one of the (if not the) best-reviewed carbon monoxide alarms we considered.

What’s Nighthawk?
Pin

We aren’t talking about the Marvel superhero. Nighthawk is a name Kidde uses for its sensor technology.

Both customers and experts alike gave this alarm high ratings, and for good reason. It has a digital display and a generous five-year warranty. And, yeah, it’s plug only, but the six-foot cord means it doesn’t have to be right by an outlet.

Even with a long cord, a plug-in alarm can be a hassle in some cases. And if you’re looking for a carbon monoxide-smoke detector combo, this isn’t right for you.

Also, if you’re big on home automation, know that this device won’t sync with a voice assistant or other equipment.

View on Amazon

Kidde KN-COSM-BA Combination Smoke/Carbon Monoxide Alarm: Best combo

4.5 out of 5 stars
4.5
Pro Bullet Smoke detector
Pro Bullet Voice warnings
Pro Bullet Battery-powered

Looking for a reliable combo alarm that’s not crazy expensive? We’ve found one.

For those who want the two-in-one safety of a smoke alarm-carbon monoxide detector combo, the KN-COSM-BA is a solid choice. This detector isn’t too expensive, and it runs on batteries rather than needing a plug or wires.

Our favorite feature, though, is the voice warnings aka voice alarm. When the alarm goes off, it vocally announces either “Fire,” or “Warning: carbon monoxide,” so you know what you’re dealing with.

Do I need a smoke alarm or fire alarm in my carbon monoxide detector?
Light Bulb

Not necessarily. Carbon monoxide gas doesn’t rise or fall, so it can usually be found in equal concentrations throughout a home.² So while you should put your smoke detector on the ceiling, you might want to disperse carbon monoxide alarms at different levels throughout your home. In that case, it might make sense for some or all of your devices to detect carbon monoxide only.

What if it breaks? Like the KN-COPP-3 carbon monoxide detector, this Kidde device comes with a five-year limited warranty.

The KN-COSMA-BA comes with a limited five-year warranty.

The downside

The Kidde KN-COSMA-BA doesn’t have a digital display. That means there’s no screen to show the carbon monoxide levels or other metrics. And, like the KN-COPP-3, it wasn’t made for smart home use. You can’t hook it up to your other devices.

View on Amazon

Nest Protect Smoke and Carbon Monoxide Detector: Best for Google Assistant

4 out of 5 stars
4
Pro Bullet Smoke detector
Pro Bullet Voice warnings
Pro Bullet Google Assistant compatibility

For all you Google Assistant users out there, this one’s for you.

If you swear by your Google Home, or if you’ve already invested in a Google Nest Secure security system, the Nest Protect is a safe bet. It’ll integrate smoothly with your existing setup. It’s also flexible; you can have it hardwired or just use batteries.

This high-tech smart device features a smoke detector and voice warnings, similar to the Kidde KN-COSMA-BA. You’ll get mobile notifications for alarm events and when the batteries need to be changed. And if you need to turn the alarm off, you’ll tap the Nest app to silence the system from anywhere.

Your device has a two-year limited manufacturer warranty to protect your Nest Protect.

It’s convenient to use remote access to silence your carbon monoxide detector/smoke alarm. But we wish there was also a more obvious button on the Nest Protect for times when your phone isn’t handy.

It took us some digging to realize that the circle in the middle, which lights up when the alarm goes off, is also the silence button. If you forget that little detail, you’ll be forced to listen to the incessant beeping of the alarm while you search for a way to turn it off.

Similarly, the device doesn’t have a digital display to show you the carbon monoxide levels. You’ll have to go to the app.

View on Amazon

Onelink Safe & Sound by First Alert: Best for Alexa

3.5 out of 5 stars
3.5
Pro Bullet Smoke detector
Pro Bullet Voice warnings
Pro Bullet Alexa compatibility
Pro Bullet Built-in Alexa speaker

Onelink is our pick for Amazon Alexa users.

Onelink is the best option if you want something to work with your Alexa-enabled smart home. The Onelink Safe & Sound is quite similar to the Nest Protect, right down to the smoke detector combo and voice warnings.

But the Onelink offers a little more than the Nest Protect. It has an Alexa speaker built right into it. The speaker doesn’t just control the carbon monoxide detector either; you can use it for other Alexa voice commands.

Lastly, with a Onelink Safe & Sound, you get a three-year warranty. It’s not as extensive as the Kidde detectors’ warranties, but it’s better than Nest Protect’s.

This bad boy’s extremely expensive. For the price of a Onelink, you could buy two and a half Nest Protects and still have enough money to get lunch from the McDonald’s dollar menu.

The Onelink also shares Nest Protect’s lack of a digital display. We think it’s cool to control your detector from a mobile app, but again, it’s also nice to look at the device and immediately know its status.

Also, you have to plug this detector in. The battery backup is for power outages, not for day-to-day use.

First Alert
Bullhorn

First Alert, the company that produces the Onelink Safe & Sound, says that it sold the first residential smoke alarm in 1958.

Kidde Battery-Operated KN-Copp-B-LPM: Budget pick

4.3 out of 5 stars
4.25
Pro Bullet Affordable
Pro Bullet Battery-powered
Pro Bullet Five-year limited warranty

The Kidde Battery-Operated KN-Copp-B-LPM is very cheap but minimalistic.

If finances are tight, this is the pick for you. The Kidde KN-COB-LP2 9CO5-LP2 is very inexpensive. But it also comes from Kidde, one of the top carbon monoxide detector manufacturers, so it should be quality even with the price cut.

This battery-powered alarm has a ten-year limited warranty. It takes just two AA batteries, which makes it relatively inexpensive to operate and keeps it safe from a power outage.

To get that low, low cost, Kidde stripped away any extras. This alarm doesn’t have a smoke detector and the digital display is tiny. And it’s not a smart product; you can’t mesh it with your connected home network.

View on Amazon

Recap: Best carbon monoxide detectors

Still deciding? Let’s run through each of our recommendations one last time.

  • If you seek a basic, traditional option, then the Kidde KN-COPP-3 is what we recommend.
  • Try this Kidde KN-COSM-BA alarm to harness the power of both carbon monoxide and smoke detection.
  • We recommend Nest’s homegrown product, Nest Protect, for Google Assistant enthusiasts.
  • Likewise, the Onelink Safe & Sound is perfect for Alexa lovers.
  • If you don’t want to spend much money, try this super cheap Kidde Battery-Operated KN-Copp-B-LPM option.

If you’re looking for a straight-up smoke alarm, check out this guide. Or, if you want more robust protection, consider a full security suite.

Methodology

We looked at 40 of the most popular consumer carbon monoxide detectors and compared the following factors:

  • Price
  • Warranty
  • Power source
  • Presence of smoke alarm
  • Presence of emergency buttons
  • Presence of low battery signal

Carbon monoxide detector FAQ

What are the symptoms of carbon monoxide poisoning?

According to the CDC, symptoms of CO poisoning are as follows:

  • Headache
  • Dizziness
  • Weakness
  • Upset stomach
  • Vomiting
  • Chest pain
  • Confusion³

These might seem like pretty distinct symptoms at first blush, but things aren’t always so straightforward in the moment.

There’s a famous Reddit tale about a man who believed his landlord was leaving him mysterious notes around his apartment. Turned out, he was actually confused due to high carbon monoxide levels in his rental—he’d written the notes himself.

Having a carbon monoxide detector means that your bewildered brain doesn’t have to play detective. You’ll know that you’re being poisoned and can get out.

PPM
Pin

Carbon monoxide gas is measured in PPM (parts per million). 101 PPM and over are considered dangerous levels.⁴

What should I do if my home has dangerous levels of CO?

Get out. You need to get some fresh air to recover. If someone is experiencing major symptoms, call 911. If not, call your local fire department.⁵

Can I get a carbon monoxide detector through my home security company?

In many cases, you can. ADT and SimpliSafe both sell carbon monoxide alarms that integrate with their systems, and they aren’t the only ones.

Ring Alarm also has an Alexa-compatible offering called a smoke and CO “listener.” Install this little beauty near your previously existing alarms. When one goes off, the listener lets you know through a mobile notification.

Where should I put my carbon monoxide detector?

Put a sensor in areas susceptible to CO buildup, like in your garage or RV or near fuel-burning furnaces, stoves, water heaters, fireplaces, and generators.

It’s also smart to put detectors in bedrooms and highly trafficked living areas. You want the detectors to be where you are so that you’ll be notified of high levels immediately.

Can I get a portable carbon monoxide detector?

Yes. For instance, you could try this Forensics Car and Aircraft Carbon Monoxide Sensor. It’s meant for vehicles, but you might be able to use it elsewhere.

There’s also the waterproof, shockproof Sensorcon. You can carry this CO alarm throughout different rooms in your house if needed—though we recommend it primarily for hotels.

What’s a limited warranty?

A limited warranty can be tricky. It’s left to the retailer’s discretion to decide what the warranty covers. So your warranty might cover accidental damage but not normal wear and tear. Or it might include the hardware but not the repair labor.⁶ Or it might be utterly void if you purchased the product through a third party, even on a reputable site like Amazon.

Be smart about your carbon monoxide detector’s warranty. Read the conditions and terms thoroughly and follow them so you aren’t on the hook for repair and replacement costs.

Sources

  1. Centers for Disease Control and Prevention, “Carbon Monoxide (CO) Poisoning Prevention.” Accessed December 1, 2021.
  2. Jason M. Carlton, Intermountain Healthcare, “Protect Your Family: Install Carbon Monoxide Alarms.” February 26, 2014. Accessed December 1, 2021.
  3. Centers for Disease Control and Prevention, “Frequently Asked Questions.” Accessed December 1, 2021.
  4. Kidde, “What Are the Carbon Monoxide Levels That Will Sound the Alarm?” October 4, 2019. Accessed December 1, 2021.
  5. Kidde, “Carbon Monoxide Poisoning FAQs.” Accessed December 1, 2021.
  6. FindLaw, “What Is the Difference Between a Full Warranty and a Limited Warranty?” Accessed December 1, 2021.

Certain content that appears on this site comes from Amazon.com. This content is provided “as is” and is subject to change or removal at any time. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product. Reviews.org utilizes paid Amazon links.

Brianne Sandorf
Written by
Brianne Sandorf
Brianne has a degree in English and creative writing from Westminster College and has spent 6+ years writing professional, research-based content. Before joining Reviews.org, she wrote safety and security content for ASecureLife.com. Her pieces and quotes are published across the web, including on MSN.com, Social Catfish, and Parents.com. Hobbies include wearing a seatbelt, wearing a life jacket, and keeping her arms and legs inside the ride at all times. Contact her at brianne@reviews.org.

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