The 8 Best Carbon Monoxide Alarms of 2019

Prioritize your safety by installing these alarms

Our editors independently research, test, and recommend the best products; you can learn more about our review process here. We may receive commissions on purchases made from our chosen links.

Our Top Picks

Best High-End: Nest Protect Smoke & Carbon Monoxide Alarm at Walmart

"Conveniently test the alarm and receive a full report right from your phone."

Best Overall: Kidde Nighthawk Carbon Monoxide Detector at Amazon

"Features a digital reading of current CO levels, to detect any leaks."

Runner-Up Best Overall: First Alert Combination Alarm at Amazon

"Built with a wireless safety network and voice alarm to alert the problem."

Best Budget: Kidde Carbon Monoxide Alarm at Amazon

"Offers reliable performance at a great price value."

Best for Long Battery Life: First Alert Detector at Amazon

"Features a 10-year battery life and easy to read display."

Best Smart Home: First Alert OneLink Carbon Monoxide Alarm at Lowe’s

"Detects CO levels with a premium home speaker that is Alexa-enabled."

Best Portable: Forensics Car Carbon Monoxide Detector at Amazon

"Trace early warnings of CO levels by adding this to your travels."

Best Multi-Pack: Kidde Code One Detector at Home Depot

"A great option for large houses or those managing rental properties."

  • 01 of 08

    Best High-End: Nest Protect Smoke & Carbon Monoxide Alarm

    Nest Protect Smoke & Carbon Monoxide Alarm, Battery (2nd gen)
    Courtesy of

    For a full-featured carbon monoxide alarm, look no further than the Nest Protect Smoke & Carbon Monoxide Alarm. This dual-purpose unit monitors for both carbon monoxide and smoke. An easy-to-use app makes it easy to keep tabs on the system, and provides additional notifications if problems are encountered.

    The Nest Protect can be ordered for either hardwired installation or battery operation. No matter which model you choose, the unit is enabled with Wi-Fi and provides instant updates to your phone if a problem is encountered or battery life is low. You can also test the alarm from your phone and receive a full report when the test is complete. But you don’t have to worry if you forget to initiate a test since the unit tests itself over 400 times a day. 

    This high-end carbon monoxide alarm links to other units installed in your home and is also compatible with products in the Google Nest family. People frequently comment on how convenient it is to silence false alarms from their phone or test the unit within the app. It also is popular for its voice function—if the alarm is triggered, the unit will tell you which room is experiencing a problem.

  • 02 of 08

    Best Overall: Kidde Nighthawk Carbon Monoxide Detector

    Kidde 900-0076-01 KN-COPP-3 Nighthawk

     Courtesy of

    Reliable and well-reviewed, the Kidde Nighthawk is a top pick for a carbon monoxide alarm. This plug-in model features a digital reading of current carbon monoxide levels (also referred to as CO) and it’s refreshed every 15 seconds. The unit includes a 9V battery backup for peace of mind and continued monitoring in the case of a power outage. 

    The easy-to-read digital display is front and center on this alarm. Many reviewers appreciate being able to see the CO level at a glance, and this information could be very useful to first responders in the event of a leak. A button labeled ‘Peak Level’ makes it easy to recall the highest recorded level of CO since the alarm was last unplugged or reset. 

    You will need to give up an outlet to plug in this carbon monoxide alarm, but the peace of mind that the Kidde Nighthawk provides is well worth it. Additionally, the unit includes extra cord, so you can plug it into an outlet and set the unit on a nearby table, shelf, or counter. 

    There are numerous rave reviews about this carbon monoxide detector and plenty of stories as to how it alerted families to dangerous CO levels. But an especially useful feature is the fact that the unit can be unplugged and carried into different rooms for an instant reading, thanks to the onboard battery backup. For under $30, the Kidde Nighthawk is a reliable, useful carbon monoxide alarm that can keep you protected.

    Want to learn more? Check out our hands-on review of the Kidde Nighthawk

  • 03 of 08

    Runner-Up Best Overall: First Alert Combination Alarm with Voice Location

    First Alert SCO501CN-3ST ONELINK Battery Operated Combination Smoke and Carbon Monoxide Alarm with Voice Location

     Courtesy of Amazon

    These carbon monoxide detectors also pull double duty as smoke alarms. But one of the favorite features of the First Alert Combination Alarm is the unit’s voice location function. 

    During set-up, program the unit for the room it’s located in—child’s bedroom, living room, guest room, etc.—for immediate identification of where the alarm is originating from. There are 11 pre-recorded locations to choose from, but no option to personalize the locations (such as: ‘Matt’s Bedroom’ or ‘Downstairs Guest Room’). These alarms are also equipped with a wireless safety network, meaning that up to 18 units can be connected within the home. When one alarm is activated, all connected units will sound the warning—including the voice alarm of which room has the problem. 

    Since these units are battery-operated and not hardwired, they’re easy to install in any location regardless of existing wiring. When the battery is low, all connected units will sound the warning and tell you which room contains the low battery. The most notable drawback is the lack of a digital CO reading, but these two-in-one smoke and carbon monoxide alarms are popular for their voice location function and easy installation.

    Not sure how to install your device? Check out our guide that shows you how to install a carbon monoxide detector.

  • 04 of 08

    Best Budget: Kidde Carbon Monoxide Alarm

    Kidde 21025778 Carbon Monoxide Alarm Battery

     Courtesy of Amazon

    You can’t put a price on safety, but this basic model of carbon monoxide alarm from Kidde is less than $15 and offers reliable performance. The Kidde Carbon Monoxide Alarm (model 21025778) operates using two AA batteries and can be placed in any room.

    This budget carbon monoxide alarm is simple but covers all the bases. An 85-decibel alarm will alert you if dangerous levels of carbon monoxide are detected. LED lights will provide visual confirmation if the alarm is triggered, and a Test/Reset button allows you to confirm that the unit is working. 

    While some people prefer a carbon monoxide detector that can be plugged in, others like the battery power of this unit. Some reviewers point out that they even travel with this unit.

    Continue to 5 of 8 below.
  • 05 of 08

    Best for Long Battery Life: First Alert Carbon Monoxide Detector with 10-Year Battery

    If you don’t have a hardwired carbon monoxide alarm and don’t want the hassle of routinely changing batteries, then consider a model with a built-in lithium-ion battery. The First Alert Carbon Monoxide Detector with 10-Year Battery (model CO710) is a popular pick for its long life and an easy-to-read display. 

    This is a sealed carbon monoxide detector, meaning you won’t be able to open the unit to change the battery. But fortunately, you won’t need to—since the included lithium-ion battery will last the life of the unit. Most safety regulations require that carbon monoxide detectors be replaced at least every 10 years, and in some cases, even more frequently. 

    With a long battery life, this carbon monoxide alarm will never wake you up in the middle of the night with the dreaded ‘low battery alarm.’ However, when the unit is approaching the end of its 10-year lifespan, it will sound an alert to let you know it’s time to replace it. Users also appreciate the fact that a digital display provides an indicator of CO concentration, peak CO levels, and the current temperature in the room.

    Check out our other reviews of the best smoke detectors available on the market today.

  • 06 of 08

    Best Smart Home: First Alert OneLink Safe and Sound Carbon Monoxide Alarm

    First Alert Safe and Sound Smart Hardwired Smoke

     Courtesy of Lowes

    For a safer smart home, install the OneLink Safe and Sound Carbon Monoxide Alarm. This two-in-one device makes no compromises and is a great carbon monoxide detector for your smart home. 

    The OneLink is equipped to detect both smoke and carbon monoxide. However, the unit also features a premium home speaker that is Alexa-enabled. You can play favorite tunes, ask Alexa about the weather, and more with this carbon monoxide detector. 

    The device is also integrated with an app for your smart devices. Using the app, you can receive alerts, track CO levels, and adjust the nightlight function of the unit. This unit operates on AC power but includes adaptor plugs that utilize existing hardwired connections. 

    At just over $200, this is a pricey carbon monoxide detector, but it offers multi-functionality that is perfect for your smart home. Reviewers consistently comment on how this is the first carbon monoxide alarm they’ve been excited to use, and with superior speakers and smart home integrations, it’s not hard to see why.

    Want to take a look at some other options? See our guide to the best wireless security systems.

  • 07 of 08

    Best Portable: Forensics Car and Aircraft Carbon Monoxide Detector

    For a portable carbon monoxide alarm to keep you protected even on the go, the Forensics Car and Aircraft Carbon Monoxide Detector has you covered. This sleek and small model weighs only 2 ounces but has a digital display and a handful of useful features. 

    This portable carbon monoxide alarm detects the presence of this gas at levels as low as 9ppm. If the gas is present for 60 seconds or more, an alarm will sound. Most household carbon monoxide detectors won’t sound an alert until levels approach 70ppm for 60 minutes or more. If you’re operating a vehicle, significantly lower levels of carbon monoxide can cause drowsiness and potentially impair your ability to safely drive. The Forensics Car and Aircraft Carbon Monoxide Detector provides early warning of CO levels and is a smart addition for your car, airplane, or travel kit. 

    The battery life is rated for up to a year, and an indicator of remaining battery life is included in the digital display. You can also check the current reading of CO levels on the display, or quick press the power button to see the max reading of CO detected by the unit since the last reset. People have used these portable carbon monoxide detectors extensively in personal vehicles, fleet vehicles, airplanes, and on trips for peace of mind and safety.

  • 08 of 08

    Best Multi-Pack: Kidde Code One Battery Operated Carbon Monoxide Detector

    Code One Battery Operated Carbon Monoxide Detector

     Courtesy of One Battery

    Since carbon monoxide alarms are limited in their detection radius, it often makes sense to have several units in operation in your home. The size of each room and overall layout will dictate how many carbon monoxide monitors you need, but the Kidde Code One Multi-Pack makes it easy to protect your whole house. 

    This carbon monoxide alarm multi-pack includes six battery-operated units. Instead of worrying about hardwiring or taking up outlet space, this model is easy to set up and move around. Three AA batteries give you about six months of power, and the unit itself has a 7-year life span. 

    Reviewers are happy with the straightforward set-up and reliable performance of these Kidde detectors. If you have a large house, manage rental properties, or need to keep back-up detectors at the ready, consider this multi-pack of carbon monoxide detectors.

Products Tested by

How We Tested

We bought a top-rated carbon monoxide alarm that our reviewer tested for weeks on end. We asked our tester to consider the most important features when using this carbon monoxide alarm, from its detection capabilities to its interconnectivity. We’ve outlined the key takeaways here so that you, too, know what to look for when shopping.

What to Look for in a Carbon Monoxide Alarm

Smoke detection The first choice you’ll want to make is whether you want a product that’s both a smoke and carbon monoxide detector. If you already have smoke detectors in your house, it will probably be less expensive to simply buy supplementary CO alarms. However, if you’re in the market for both, you can cross two items off your to-do list with 2-in-1 units.

Installation Do you want an alarm that’s plugged into an outlet, battery-powered, or hardwired? Battery-powered units can be placed anywhere, but you’ll have to stay on top of their battery status. Plug-in products won’t die on you, but you’re limited in where you can put them. Hardwired units, on the other hand, require more complex installation.

Interconnectivity Many 2-in-1 CO and smoke detectors can be interconnected, meaning if an alarm goes off on the first floor of your home, it will trigger the alarms on the second floor as well. This ensures you won’t ever miss the alarm. However, if the alarm you choose can’t be interconnected, you will have to buy numerous units to cover your entire home.

Test Results: Nest Protect Smoke & Carbon Monoxide Alarm (Best High-End)


What We Like

  • Connects to smart devices

  • Early warning system

  • Auto-testing and automatic battery monitoring

What We Don't Like

  • Pricey

Nest Protect Smoke & Carbon Monoxide Alarm
The Spruce
Nest Protect Smoke & Carbon Monoxide Alarm
The Spruce
Nest Protect Smoke & Carbon Monoxide Alarm
The Spruce

Our tester loved this device for its “loud and audible” alarms, smart device app integration, easy setup, and motion-sensor night light. He reported, “The device uses a constantly-updating carbon monoxide detection algorithm, checks its own battery level 400 times a day, and quietly tests its speaker and horn once a month via Sound Check.” And while it is an expensive unit, our reviewer felt it was worth the investment. “Simply put, Nest has made one of our most essential home products into a smart, user-friendly, and intuitive device,” he declared.