The Best Carbon Monoxide Detectors, Tested

Protect your home from this silent danger with a not-so-silent alarm.

Best Overall

The Best Carbon Monoxide Detector Option: Kidde Nighthawk Carbon Monoxide/Explosive Gas Alarm

Kidde Nighthawk Carbon Monoxide/Explosive Gas Alarm

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Best Bang for the Buck

The Best Carbon Monoxide Detector Option: Kidde Battery-Operated Carbon Monoxide Detector

Kidde Battery-Operated Carbon Monoxide Detector

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Best Plug-In

The Best Carbon Monoxide Detector Option: First Alert CO600 Plug-In Carbon Monoxide Detector

First Alert CO600 Plug-In Carbon Monoxide Detector

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A home fire safety plan is incomplete without a set of carbon monoxide detectors, which sense this odorless, poisonous gas and alert residents to its presence. Without a comprehensive system of carbon monoxide detectors, a family can be at serious risk. This gas can overwhelm a home’s occupants overnight as they sleep, and typical symptoms—dull headache, dizziness, and confusion—may not be noticed.

There are a variety of different types of these crucial devices, so we opted to test a number of the most popular models to see how they fare in real-life situations. Read on to learn how to choose a model, and see why the units tested met our standards to be considered among the best carbon monoxide detectors available.

  1. BEST OVERALL: Kidde Nighthawk Carbon Monoxide/Explosive Gas Alarm
  2. BEST BANG FOR THE BUCK: Kidde Battery-Operated Carbon Monoxide Detector
  3. BEST PLUG-IN: First Alert CO600 Plug-In Carbon Monoxide Detector
  4. BEST HARDWIRED: Kidde Firex AC Hardwired Carbon Monoxide/Smoke Alarm
  5. BEST COMBINATION: First Alert SCO5CN Smoke/Carbon Monoxide Detector
  6. BEST SMART UNIT: Google Nest Protect Smoke and Carbon Monoxide Alarm
  7. BEST DIGITAL DISPLAY: X-Sense CO03D Carbon Monoxide Alarm
  8. BEST MULTIPACK: First Alert SC7010BV-3 Talking Smoke/CO Alarm 3 Pack
The Best Carbon Monoxide Detector Options
Photo: Tom Scalisi

How We Tested the Best Carbon Monoxide Detectors

We wanted to recommend only the best carbon monoxide detectors, so we did our homework. We performed extensive product research to choose some of the top-rated models on the internet and then performed hands-on testing to ensure they had the goods.

First, we installed each of the models according to the manufacturer’s instructions. Then we attempted to test each model with a can of faux carbon monoxide. We quickly realized that this part of the test was flawed, as most models require prolonged presence of carbon monoxide to alert. However, some models had test ports and were compatible with the test.

Next, we activated each of the carbon monoxide detectors and traveled to the far side of the house to ensure that we could hear them. We learned that the sirens are always effective, but that sometimes voice alerts can be too hard to hear (thankfully, they all have sirens as well). The final step was to test additional features, such as recall buttons and apps, getting to know what each model could do.

The carbon monoxide detectors that passed our tests were given awards based on their strengths. Those that didn’t were tossed aside, as they didn’t provide enough value to be worthy.

Carbon Monoxide and How It’s Detected

Carbon monoxide (CO) is generally a byproduct of combustion: Any appliance that uses a fuel source (a water heater, furnace, or boiler, for example) produces carbon monoxide when it’s running. That excess carbon monoxide is meant to be released outside through chimneys and vents. These appliances are extremely safe when working properly, but if something goes wrong, the carbon monoxide can build up to dangerous levels.

Carbon monoxide is measured in parts per million (PPM). Exposure of 50 PPM is safe for up to 8 hours, while 150 PPM is dangerous after 50 minutes, and 1,600 PPM can kill a healthy adult in less than 1 hour.

Carbon monoxide detectors are so important because the gas is colorless and odorless, so it’s impossible for people to sense its presence until it’s too late. Carbon monoxide detectors track levels of the gas over time and sound a loud alarm when those levels exceed certain parameters. For instance, a 50 PPM measurement will activate most alarms after 8 hours, 150 PPM within 50 minutes, and 400 PPM within 15 minutes.

For testing purposes of the models reviewed here, a can of faux carbon monoxide was used. However, since most detectors require prolonged presence of carbon monoxide to provide an alert, this method was far from foolproof. Fortunately, some models had test ports and that allowed for testing.

Detector Locations

The general consensus is that a carbon monoxide detector should be installed on every floor of a house and either inside (or just outside) of every bedroom. A unit should be placed in the basement and the garage as well.

Testing Intervals

To ensure proper operation, follow the same guidelines used for smoke detectors. Carbon monoxide detectors should be tested monthly, and batteries should be replaced at least once a year, regardless of whether the low-battery alarm sounds.

Device Lifespan

Even if the batteries in a carbon monoxide detector are changed regularly, the detectors themselves don’t last forever. Check the back of the home’s devices to learn what their expected lifespan is—usually between 5 and 7 years. If homeowners can’t remember when they purchased the device, they should consider replacing it now.

The Best Carbon Monoxide Detector Options
Photo: Tom Scalisi

Our Top Picks

Carbon monoxide detectors are a crucial component to home safety. Consider the following models suited to a variety of situations, and read on for further understanding of the features to look for and how to choose the best model for a particular set of needs.

Best Overall

Kidde Nighthawk Carbon Monoxide/Explosive Gas Alarm

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This Kidde carbon monoxide detector does more than simply sense dangerous levels of carbon monoxide; it can also detect the presence of explosive gases. Its digital display alerts to real-time carbon monoxide levels in the home, while the peak-level function shows the highest point reached since it was last reset.

This model can plug directly into an outlet or operate with the included corded adapter, and it has battery backup. Though explosive gas detection is not immediate, and occupants will likely smell gas before the detector goes off if they’re awake, it’s a great safety feature for peace of mind when the household is asleep.

In testing, there were quite a few things to like about the Kidde Nighthawk. First, it was one of the only detectors that was responsive to our carbon monoxide test, alerting us that there were 157 PPM in the air at the peak. Also, we liked the flexible mounting options, as it can be installed anywhere within 7 feet of an outlet thanks to the included cord. While we weren’t a big fan of the size (it’s much bigger than the other plug-in models), we recognized that the digital display does require some extra size, and it’s worth having.

Product Specs

  • Type: Carbon monoxide/explosive gas
  • Power source: Plug-in or battery
  • Interconnectivity: None

Pros

  • Flexible plug-in allows use within 7 feet of an outlet
  • Detects both carbon monoxide and explosive gas
  • Digital reading displays the amount of gas in the air
  • Battery backup ensures unit function, even in power outages

Cons

  • Large, bulky design

Get the Kidde Nighthawk carbon monoxide detector at Amazon.

Best Bang for the Buck

Kidde Battery-Operated Carbon Monoxide Detector

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Reliable protection against poisonous levels of carbon monoxide needn’t be expensive, so those on a budget may wish to look into Kidde’s battery-operated carbon monoxide detector. This detector, which uses three AAA batteries, has a handy lockout feature on the battery door to prevent it from shutting without batteries in place, ensuring the home is always protected.

This model has a loud 85-decibel alarm to alert residents if it detects carbon monoxide. It also has a low-battery signal, a built-in test button, and two LEDs—a green LED indicates proper operation and a red LED indicates dangerous levels of carbon monoxide.

We found the beauty of the Kidde Battery-Operated Carbon Monoxide Detector to be its simplicity. After installing the batteries and mounting it to the wall with two anchors and screws, this model was ready to go. We also liked how compact it is—as well as the budget-friendly price tag. However, it’s fairly basic, so shoppers looking for interconnectivity or smart features will want to keep shopping.

Product Specs

  • Type: Carbon monoxide only
  • Power source: Battery
  • Interconnectivity: None

Pros

  • Compact size
  • Low price makes having multiple units affordable
  • Very simple to set up and install

Cons

  • No additional features

Get the Kidde battery-operated carbon monoxide detector at Amazon.

Best Plug-In

First Alert CO600 Plug-In Carbon Monoxide Detector

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Folks who’d prefer the very simplest form of carbon monoxide detection should consider the First Alert CO600. This device plugs into a standard wall outlet—no need for batteries or hardwired connections—plus its compact design and prong placement won’t block both outlets in a double outlet.

This model features a loud 85-decibel alarm to alert residents to the presence of dangerous levels of carbon monoxide. It has one button for testing and resetting, and no digital display or settings to fool around with, making it as straightforward as carbon monoxide detection can get.

There aren’t a lot of features to discuss with the CO600. It’s just a bare-bones, affordable carbon monoxide detector that installs quickly and does its job. It responded to the carbon monoxide test (it does have a port in front of the sensor), and it was loud enough to alert folks from anywhere in the house. Shoppers should know, however, that should the power go out, the model will shut off, as there’s no backup battery.

Product Specs

  • Type: Carbon monoxide
  • Power source: Plug-in
  • Interconnectivity: None

Pros

  • Very simple design—literally just plug and play
  • Loud siren
  • Did respond to CO test, thanks to test port on the front of the unit

Cons

  • Shuts off when power goes out

Get the First Alert CO600 carbon monoxide detector at Amazon or Lowe’s.

Best Hardwired

Kidde Firex AC Hardwired Carbon Monoxide/Smoke Alarm

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Hardwired smoke detectors tend to be basic, but the Firex model from Kidde has some great features. For one thing, the hardwired smoke and carbon monoxide detector shouts voice alerts, warning users of the presence of smoke or carbon monoxide to ensure they understand the hazard involved.

This model from Kidde is also flexible, linking to the existing fire alarm system with the included wiring plug or operating off of a 9-volt battery installed in the front of the unit. And since it is hardwired, it can interconnect with up to 24 other devices, including other smoke, carbon monoxide, or heat detectors.

While the Kidde Firex combination smoke detector is a hardwired model, we appreciated the flexibility of power sources between wired power or batteries. The voice alerts proved to be very loud, intense, and clear. We did find the base slightly finicky to deal with, as there’s a small release mechanism that we needed to locate, but beyond that, using this smoke detector was extremely simple, down to the front-mounted battery.

Product Specs

  • Type: Smoke/carbon monoxide
  • Power source: Hardwired or battery
  • Interconnectivity: Yes, with up to 24 other devices when hardwired

Pros

  • Hardwired plug makes installing it into an existing system easy
  • Battery backup ensures it can operate even if the power is out
  • Very loud, clear, and intense voice alerts

Cons

  • The base was slightly finicky to operate

Get the Kidde Firex carbon monoxide detector at Amazon.

Best Combination

First Alert SCO5CN Smoke/Carbon Monoxide Detector

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Rather than the latest smart technology, some folks just want a dependable, easy-to-use detector they can install and check several times a year. This First Alert combination model is exactly that. It features a photoelectric sensor for smoke detection and an electrochemical sensor for carbon monoxide detection—both tried-and-true, reliable sensors.

This combination smoke and carbon monoxide detector is battery-powered, allowing it to be easily installed anywhere. It also has a loud 85-decibel alarm to ensure it wakes dozing residents. Locking pins in the base that the user can install ensure that the battery drawer stays shut, keeping the battery in place. We were able to trip this model with the carbon monoxide test (it has a port for the straw).

But we’ll admit that the First Alert battery drawer confused and frustrated us. Rather than swinging outward from the unit, it pulls straight out like a dresser drawer. Hopefully it’s something users can get used to, since beyond that, we found the First Alert to be very effective and easy to install.

Product Specs

  • Type: Smoke/carbon monoxide
  • Power source: Battery
  • Interconnectivity: None

Pros

  • Features 2 reliable detection sensors for user peace of mind
  • Base has locking pin to prevent battery disconnection
  • Easy to install; requires no wiring or power source

Cons

  • Confusing battery drawer

Get the First Alert SCO5CN carbon monoxide detector at Amazon.

Best Smart Unit

Google Nest Protect Smoke and Carbon Monoxide Alarm

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The Nest Protect Smoke and Carbon Monoxide Alarm from Google is a worthy choice for smart homes. It detects both smoke and carbon monoxide and can alert to a problem even if household members aren’t present.

When the Nest activates, it alerts an app, the smart-home system, and its central monitoring company through the homeowner’s Wi-Fi network. Being interconnect capable, it will also activate other smart-alarm devices. This model provides voice alerts about the condition and the room in which the hazard is detected, and this can be a big help for groggy residents in the middle of the night.

The Google Nest Protect was one of our favorite models in the test. It provides clear voice alerts that are easy to understand and even has a cool yet unobtrusive appearance (it looks like a speaker). Setting up the app was easy (though it is an extra step that other models tested did not require) via the included QR code on the back of the detector. Plus, the base allows for plenty of swivel, meaning users can easily align their Nest Protect with the home’s walls for a square, clean installation. Our one complaint is that, despite easily adding this model to the Nest app, we haven’t been able to add it to our Google Home app.

Product Specs

  • Type: Smoke/carbon monoxide
  • Power source: Rechargeable battery
  • Interconnectivity: Yes, with other Nest devices

Pros

  • Clear, specific alerts to hazard condition and room where detected
  • Physical installation and setup with the app are both very simple
  • Good-looking design
  • Swiveling base allows for perfect alignment in installation

Cons

  • Wouldn’t link with our Google Home app

Get the Google Nest carbon monoxide detector at Amazon or The Home Depot.

Best Digital Display

X-Sense CO03D Carbon Monoxide Alarm

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When it comes to having enough coverage for an entire home, purchasing a set of detectors may make the most sense. With this three-pack of combination smoke and carbon monoxide detectors, users can cover most of their fire safety needs. Each unit has a built-in battery with a 10-year lifespan. Each detector in this set senses both smoke and carbon monoxide.

This carbon monoxide sensor takes readings and displays the PPM on the easy-to-read LCD display. These units each have an LED light that indicates green for proper function, yellow for a fault, and red for an alarm condition.

We have some experience with X-Sense products, and in the past we weren’t fans. However, it seems like the company addressed some of the issues that bothered us previously to create a high-quality, streamlined carbon monoxide detector. We found the digital display to be very easy to understand, providing real-time readings to alert to the conditions in the home, even if the detector does not sound an alarm. We also like that this model is low profile and compact while still giving an easy-to-see display. We would have prefered a recall button that displayed the highest detected levels since last reset, but otherwise, it worked well and established our faith in X-Sense.

Product Specs

  • Type: Carbon monoxide
  • Power source: Battery
  • Interconnectivity: None

Pros

  • Slim, compact design yet with an easily understood digital display
  • Real-time readings for carbon monoxide levels within the air
  • Users needn’t check digital display to know overall condition

Cons

  • No recall button

Get the X-Sense carbon monoxide detector at Amazon.

Best Multipack

First Alert SC7010BV-3 Talking Smoke/CO Alarm 3 Pack

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If those old smoke detectors are nearing the end of their life (typically 10 years), it may be time to look into a multipack like First Alert’s SC7010BV-3 Talking Smoke/CO Alarm. This pack of three detectors gives users a good start on replacing aging hardwired or battery-powered smoke and carbon monoxide detectors. Its 11 preprogrammed locations that alert users to exactly where the danger is coming from is a big bonus.

The SC7010 models feature voice alerts that clearly state the hazard at play, helping disoriented residents understand what’s going on better than standard beeps. When hardwired, these devices can interconnect with other alarms throughout the home.

In testing, we found programming the location for these units to be very simple—surprising, considering there is only one button to work with. However, the speaker did sound a bit muffled, so those voice locations might not be as clear as some folks might require. It does have an accompanying alarm, though. We also liked that these models come with easy-to-wire plugs and bases that proved simple to install.

Product Specs

  • Type: Smoke/carbon monoxide
  • Power source: Battery or hardwired
  • Interconnectivity: Yes, when hardwired

Pros

  • Voice alerts to state precise hazard and location
  • Multipack
  • Choice of 11 locations
  • Programming devices to the location is very easy

Cons

  • Speaker sounded slightly muffled

Get the First Alert SC7010BV-3 carbon monoxide detector at Amazon or Lowe’s.

Jump to Our Top Picks

What to Consider When Choosing the Best Carbon Monoxide Detector

Types of Carbon Monoxide Detectors

There are two types of carbon monoxide detectors on the market: stand-alone and combination models. Choosing the correct type for a home depends on several factors.

Stand-Alone

A stand-alone carbon monoxide detector’s only job is to detect and measure the levels of this gas in the home. Battery-operated models can be placed nearly anywhere and are the more popular choice. For a more stationary placement, choose a plug-in detector. These models often have digital readouts that display the current level of carbon monoxide being detected.

Combination

Combination units are multipurpose, monitoring carbon monoxide levels while also detecting smoke or explosive gases. The benefit of combination units is that they take a lot of the planning and guesswork out of building a fire safety system. The downfall is that for optimal use, combination carbon monoxide detectors shouldn’t be placed close to gas or oil-fired appliances. In that situation, a stand-alone smoke detector is best used with a separate stand-alone carbon monoxide detector installed farther away.

Contrary to popular belief, a standard carbon monoxide detector alone will not detect the presence of explosive gases. Explosive gases don’t contain carbon monoxide unless they’re accompanied by burnt fuel. However, carbon monoxide detectors equipped with explosive gas detection capabilities will pick up on these gases and alert residents to their presence.

Battery-Powered, Plug-In, or Hardwired?

Carbon monoxide detectors can be purchased with a few different power-supply options:

  • Battery-powered models don’t require outlets or pre-existing wiring and can be placed virtually anywhere in the home. This convenience makes it a smart idea to put an easy-to-install battery-powered unit in a garage workshop that uses propane heat.
  • Plug-in models require an outlet. This drastically reduces the flexibility of installation but, should the power go out, these units do have battery backups. Plug-in models are useful for extra protection in areas that already include smoke detectors.
  • Hardwired models use pre-existing fire-alarm wiring and battery backups for their power source. Hardwired units are the most desirable and should be used wherever possible, but not every home has specific wiring for fire alarms to run to every room.

Depending on the situation, a comprehensive system could include units from all three categories.

UL Listing

Just like smoke detectors, carbon monoxide detectors must be listed by Underwriters Laboratories (UL). The UL listing on the back of the unit indicates that the design was tested and passed UL’s stringent requirements. Considering how important carbon monoxide detection is, purchase only UL-listed models.

Digital Displays

Digital displays may seem like a gimmick, but they actually serve a fairly important purpose. These units will display the PPM of any amount of carbon monoxide they detect, even if the alarm mode needn’t be activated. This can help residents determine if there is more baseline carbon monoxide in their home than they thought; a standard carbon monoxide detector won’t offer this feature.

Interconnectivity

Carbon monoxide detectors that can be programmed or wired with other alarm devices in the home through radio-frequency, Wi-Fi, or direct wiring are considered interconnect-capable units.

With homes rapidly becoming more connected and smart, interconnect-capable units can be an added benefit for those comfortable with linking household systems together. For example, an interconnected carbon monoxide activation in the garage will trigger other alarm devices in the home, which will alert the occupants no matter where they are in the house. If the device reports back to a central monitoring station, an alarm company will notify first responders and send help without the resident even picking up the phone. This can be an especially huge benefit at night, when sleepers might not hear the garage alarm sound and when symptoms of carbon monoxide poisoning are less likely to be noticed.

Smart Features

Detection devices have joined the ranks of smart appliances and fixtures, like refrigerators and faucets. These models are often combination smoke and carbon monoxide detection units. They can communicate with a smartphone app, base station, or smart-home system. They can be programmed to describe the area and type of device that’s been activated as well as provide real-time condition updates, such as room temperature, to an app.

FAQs

Although you’ve read up on carbon monoxide detectors and how to choose one, you may still want more information on purchasing and using these essential devices. Check out the answers to the most frequently asked questions about the best carbon monoxide detectors to be more fully informed.

Q. Where is it best to place a carbon monoxide detector?

Carbon monoxide is slightly lighter than air and will travel with warm, rising air, so the best height is about 5 feet above the floor. Also, place the detector in a common hallway outside of sleeping areas, if not in the bedrooms themselves. Make sure there is at least one carbon monoxide detector on each floor and inside a garage. Be sure to follow placement and usage instructions provided by the manufacturer of the unit.

Q. How many carbon monoxide detectors do I need for my home?

The Centers for Disease Control and Prevention recommend installing at least one carbon monoxide detector per floor. With that said, the more the better.

Q. Is it better to have a battery or plug-in carbon monoxide detector?

They each have their benefits, and one is not more effective than the other. In fact, for the best coverage, you might find a combination of battery, plug-in, and hardwired detectors could be the best move.

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Tom Scalisi

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Tom Scalisi is a freelance writer, author, and blogger with a passion for building. Whether it’s a DIY project or an entire website, Tom loves creating something from the ground up, stepping back, and admiring a job well done.

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