The Best Carbon Monoxide Alarms to Keep You Safe

The Kidde Nighthawk Carbon Monoxide Detector is reliable and affordable

We independently research, test, review, and recommend the best products—learn more about our process. If you buy something through our links, we may earn a commission.

Best Carbon Monoxide Alarms

The Spruce / Chloe Jeong

Because carbon monoxide is a colorless, odorless gas that can be deadly, a carbon monoxide detector is a must-have for every home.

We researched dozens of the most popular models available now, evaluating ease of assembly and installation, effectiveness, and value. Our top choice, the Kidde Nighthawk Carbon Monoxide Detector, is reliable, affordable, and has a power failure backup mode.  

Here are the best carbon monoxide alarms.

Our Top Picks

Best Overall: Kidde Nighthawk Plug-In AC/DC Carbon Monoxide Alarm Detector

5
Kidde KN-COPP-3 Nighthawk Plug-In Carbon Monoxide Alarm with Battery Backup
Courtesy of Amazon.com.
What We Like
  • Digital display

  • Plug-in and battery power

What We Don't Like
  • No smoke detector

  • No voice alarm

Because safety is such a major concern, we recommend leaning toward a product that has two sources of power to ensure that you always know that your home is safe. The Kidde Nighthawk Carbon Monoxide Detector is a plug-in unit with a battery backup. Even if you lose power, the batteries will ensure that the alarm still functions—and if you aren’t on top of changing the batteries, the continuous plug-in power is there, too. You can use this alarm plugged into a wall outlet (most of which happen to be at ideal levels to detect carbon monoxide), wall-mounted, or on a table.

We also like the digital display that tells you exactly what the level of carbon monoxide is at any given moment. This helps interpret the many possible alarms that carbon monoxide detectors can give, such as low battery or end-of-unit-life.

Power Source: Plug-in (battery backup) | Voltage: 9 volts | Digital Display: Yes | Smoke Detector: No

Kidde Nighthawk AC Plug-In Operated Carbon Monoxide Alarm

The Spruce / Stacey Nash

What Testers Say

"The Nighthawk has only two buttons, one of which is a test button. Once we got the battery in and the unit installed, we tested the alarm. The volume definitely gets your attention. There were children in another room, and they were on high alert once the alarm started sounding."—Stacey L. Nash, Product Tester

Best with Smoke Detector: Kidde Battery-Operated Combination Smoke/Carbon Monoxide Alarm with Voice Warning

4.8
Kidde Smoke & Carbon Monoxide Detector

Courtesy of Amazon

What We Like
  • Combo smoke and carbon monoxide detection

  • Voice alert

  • Visual alert

What We Don't Like
  • Not hardwired

If you want a unit that can alert you to dangers from both fire/smoke and carbon monoxide, the Kidde Smoke and Carbon Monoxide Detector is easy to install, effective option. The voice alert feature tells you which danger you need to take action to deal with in a calm, easy-to-understand voice. It also has a visual LED alert to provide another means of notification. It operates on a battery, but you can still connect it to other Kidde products as part of a larger system if you want.

Power Source: Battery | Voltage: 1AA battery (1.5 Volts) | Digital Display: No | Smoke Detector: Yes

Kidde Battery-Operated Combination Smoke and Carbon Monoxide Alarm

 The Spruce / Katie Begley

What Testers Say

"We didn’t have any false alarms during the month we tested the Kidde combination alarm in our room. We have other Kidde products installed around our home and have only experienced false alarms due to cooking mishaps in the kitchen as cooking smoke is a common trigger for false smoke alarms."—Katie Begley, Product Tester

Best Budget: Kidde Battery-Powered Carbon Monoxide Detector

 Kidde Battery-Powered Carbon Monoxide Detector

Courtesy of Amazon

What We Like
  • Audible alarm

  • Easy to install

  • Budget-friendly

What We Don't Like
  • No digital display

Those looking for a reliable carbon monoxide detector that will keep your home safe without any extra bells and whistles will appreciate the Kidde Carbon Monoxide Detector. At less than $15, this battery-operated option is an affordable investment in your family’s safety that will work with any budget. When it detects unsafe levels of carbon monoxide, it sounds an 85 decibel alarm which will wake up your family at night or alert you during the day. It's easy to mount on the wall or use on a tabletop, and even includes two AA batteries—adding to the cost savings.

Power Source: Battery | Voltage: AA batteries (1.5 volts) | Digital Display: No | Smoke Detector: No

Best Splurge: Google Nest Protect 2nd Generation

5
Nest Protect Smoke & Carbon Monoxide Alarm, Battery (2nd gen)

Amazon

What We Like
  • Integrates with Google smart home products

  • Detects smoke and carbon monoxide

  • Modern-looking

  • Expensive

The Google Nest Protect is the most aesthetically-pleasing and high-tech option on this list, covering all of your home's safety needs in a futuristic-looking console that can be mounted on the wall and accessed via your smartphone. You can monitor the smoke and carbon monoxide levels remotely, receive alarms on your phone as well as via a voice alarm from the unit, and even check on the battery life. This is a pretty expensive detector and alarm, though, so just be ready to pay a hefty price for its advanced features and integration with your Google home devices.

Power Source: Battery or hard-wired | Voltage: 1.5 volts | Digital Display: No | Smoke Detector: Yes

Best Plug-In: FIRST ALERT CO605 Plug-In Carbon Monoxide Detector

First Alert CO605 Plug-In Carbon Monoxide Detector

Courtesy of Amazon

What We Like
  • Detects carbon monoxide from anywhere in room

  • Easy installation

  • Budget-conscious

What We Don't Like
  • No digital display

The sensor in this carbon monoxide alarm from First Alert can work no matter where the alarm is located in your room. This provides additional flexibility for those who want to plug in the detector in an out-of-the-way outlet or who don’t have as many options available based on the electrical outlet set up in their home. It does come with a battery backup, which we always recommend when considering a plug-in model. While it doesn’t have a fancy display, it will still provide the alarm that you need to ensure your home’s safety against deadly carbon monoxide poisoning without breaking the bank.

Power Source: Plug-in | Voltage: 120 volts | Digital Display: No | Smoke Detector: No

Best Battery: Kidde 10 Year Worry-Free Sealed-In Lithium Battery Carbon Monoxide Detector

Kidde 10 year worry-free carbon monoxide alarm

Courtesy of Home Depot

What We Like
  • Installed lithium battery

  • No need to change battery

  • Easy installation

What We Don't Like
  • No smoke detection

  • No digital display

Even though this carbon monoxide detector is battery-powered, the installed lithium battery is good for the 10-year lifespan of the alarm. This means that you can enjoy the convenience of a battery-powered unit without ever worrying about changing the battery. It only detects carbon monoxide and doesn’t have a digital interface, but the convenience of setting it and forgetting it can’t be beaten.

Power Source:  Battery | Voltage: 3 volts | Digital Display: No | Smoke Detector: No

Best Hardwired: First Alert AC Hardwired Combination Smoke and Carbon Monoxide Detector

AC Hardwired Combination Smoke and Carbon Monoxide Detector with Voice Alert

Courtesy of Home Depot

What We Like
  • Smoke and carbon monoxide detection

  • Installation adaptors

  • Voice and location alerts

What We Don't Like
  • No digital display

This handy unit detects slow, smoldering fires, high levels of carbon monoxide, and heavy smoke. It is hardwired but also has a battery backup to make sure that even if you lose power, the unit itself still works. One of the best features of this First Alert system is that it alerts you using a voice alert and provides the location of the source. Hardwired systems can be a bit more challenging to install, but the First Alert combo alarm comes with adaptors to make it compatible with any other hardwired mounts that you already have.

Power Source:  Hardwired (with battery backup) | Voltage: 120 volts | Digital Display: No | Smoke Detector: Yes

Best Multi-Pack: First Alert BRK 9120B-3 Hardwired Smoke and Carbon Monoxide Detector with Battery Backup, 3 Pack

 FIRST ALERT BRK SC9120B-3 Hardwired Smoke and Carbon Monoxide (CO) Detector

Courtesy of Amazon

What We Like
  • Savings over single purchase

  • Integrate together

  • Hardwire with battery backup

  • Smoke and carbon monoxide detector

What We Don't Like
  • No digital display

It is a good idea to put a carbon monoxide detector on each level of your home or near each bedroom. This is especially important for those with gas appliances or utilities that could be a source of a carbon monoxide leak. This is why buying a multi-pack of carbon monoxide detectors is so common and can save money. The 3-pack from First Alert is available in a hardwired version with a battery backup to ensure that you are always protected. You can also purchase this reliable detector in a 6-pack if you have multiple homes to outfit. These alarms can be linked together so that they will all sound, no matter where the unsafe levels of carbon monoxide are detected.

Power Source: Hardwired (with battery backup) | Voltage: 1.5 volts | Digital Display: No | Smoke Detector: Yes

Final Verdict

Our top pick is the Kidde Nighthawk Carbon Monoxide Detector for its great features, budget-friendly price, and easy installation. The two power sources (plug-in and battery) and the digital display make it the top choice for us. If you have the room in your budget, the smartphone compatibility of the Google Nest Protect Smoke Alarm, Detector, and Carbon Monoxide Detector (view at Amazon) makes it easy to monitor and respond to any safety hazards in your home—no matter where you are.

What to Look for in a Carbon Monoxide Alarm

Smoke detection

Some carbon monoxide detectors can do more than just monitor for unsafe CO levels. They can also alert you to smoke or slow, smoldering fires in your home. These combination units can be more expensive than a carbon monoxide-only detector, but still cheaper and easier to install than two separate CO and smoke detectors individually.

Installation

Hardwired units are the most complicated to install, especially if you do not already have a base station with electrical wires run. Some have adaptors that allow you to mount their unit on another company’s base without any major changes to your home. A plug-in carbon monoxide detector is easier to install, as long as you have an accessible power outlet. A battery-powered unit is the easiest to install, since all you need is a place to hang the detector on the wall or set it on a flat surface.

Interconnectivity

If you have a large home, you may want to prioritize having a detector that connects to other units in your home. This will ensure that you hear the alarm no matter where you are. Some of the high-end models also connect to your smart home or mobile devices, offering another way for you to stay connected.

Why Trust The Spruce?

This article was researched and written by Katie Begley, a freelance writer specializing in home and family products. Katie has been writing for The Spruce since 2019. All of the carbon monoxide detectors that Katie included monitor for unsafe levels of CO in the home, with special mention made of features that take safety to the next level, such as multiple sources of power or additional smoke monitoring.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Carbon Dioxide Health Hazard Information Sheet. United States Department of Agriculture.