8 Highly Sensitive Carbon Monoxide Detectors to Secure Your Home or Office

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Last updatedLast updated: June 23, 2021
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Carbon monoxide detectors are extremely important products to include within your home. For a relatively small investment, the detector can keep you aware of CO levels becoming dangerous in your home, which is something that can be fatal. There are models to suit every budget and circumstance, from basic carbon monoxide detectors to a more advanced detector with smart functionality for linking to other devices. The best carbon monoxide detector units also tend to include smoke detector capabilities.

The features we have reviewed include both safety and ease-of-use. We’ve used information such as the type of sensor, the way the detectors are powered and other more practical information such as the dimensions, and whether there is a smoke detector inbuilt within the alarm to double the functionality and turn the detector to an even better proposition. Our top-rated product, the Nest Protect Smoke and CO Alarm is an example of a smoke and carbon monoxide detector.

Our team has spent weeks doing thorough research on these items as we want to ensure that only the best quality detectors are recommended on our site to keep you and your family safe. Our research includes a buying guide at the end of the article, to help you fully understand the importance of detecting CO. Before this, we have a simple overview table and then in-depth reviews of the individual CO detectors we’ve recommended. There truly is a model to suit everyone’s needs and make sure you aren’t taking any risks.

Top 8 Carbon Monoxide Detectors Review 2021


Nest Protect Smoke and CO AlarmEditor's Choice

  • Sensor: not specified
  • Power: battery-powered
  • Smoke detector: yes
  • Dimensions: 5.3 x 1.5 x 5.3 inches

Extra features: features several pre-installed languages; connects to your phone for alerts and easier control; self-tests automatically; 10-year battery life

The editor’s choice on our list is this smart smoke and carbon monoxide detector by Nest. It has an exceptional number of features which can keep users safe and add to the ease of use for their CO detector.

Being a smart device means that this can send you alerts directly to your phone or tablet and let you know when battery is low or when there is an issue.

A very intelligent safety feature is that Nest Protect can let you know where the smoke or CO levels are high, to help you act upon it.

The lights on the Nest Protect automatically light up when you walk past to give some extra light.

The smart sensor within does a wonderful job of picking up smoke or CO and justifies the extra price you may pay for this as it is not a cheap product. All in all, this is probably the best CO detector you can find on the market today, and if you’re after a unit with plenty of advanced features, this model definitely won’t disappoint.

What do we love it for?

  • Can link to smartphones and give notifications and insight
  • Lights up when needed
  • Can notify when battery is low
  • Smoke detector built-in

What were we disappointed with?

  • One of the most expensive options on the market

First Alert Dual-Power Carbon Monoxide Detector Alarm Best Plug In Carbon Monoxide Detector

  • Sensor: electrochemical
  • Power: plug-in with battery backup
  • Smoke detector: no
  • Dimensions: 8.4 x 6.9 x 3 inches

Extra features: digital display; 7-year warranty; comes with 2 AA batteries

The First Alert Dual-Power Carbon Monoxide Detector Alarm is the best plug in carbon monoxide detector on the list with a brilliant electrochemical detector.

Being plug in gives an extra safety advantage as you can have a set of batteries installed too, as a backup for if anything goes wrong with your power. This double protection means you won’t ever be without CO detection.

Though this doesn’t have an inbuilt smoke detector and it also isn’t compatible with phones or other devices, it has an old fashioned alarm which can let you know when the Carbon Monoxide level is too high. This alarm is 85-decibels and therefore certain to be noticed even in the middle of the night.

To save money, you can even purchase this in multi-packs should you need multiple detectors. This can save you some money on the overall cost, but they aren’t the most expensive detectors anyway, and they are very reliable.

Why did it make our list?

  • Excellent, reliable sensor
  • Loud and clear alarm which can be head any time, even when you’re sleeping
  • Good value-for-money and the option to buy multiple models at once
  • Backup battery system and easy plug in

What is not ideal about it?

  • No smart functionality
  • No built-in smoke detector, so this will need to be bought separately

UEi Test Instruments CO71A Carbon Monoxide DetectorBest Portable Carbon Monoxide Detector

  • Sensor: electrochemical
  • Power: battery-powered
  • Smoke detector: no
  • Dimensions: 1.6 x 1.9 x 4.9 inches

Extra features: CO detection from 1 to 999 ppm; 3-year warranty

This is the best portable carbon monoxide detector on our list. While some people are looking for detectors which can sit in one space in their home ready to alert them of any high levels, others need a handheld CO detector which they can take out and about with them.

For instance, if you are in a factory and need to monitor the CO levels in different areas, rather than having models in every area, you can take the UEi Test Instruments CO71A Carbon Monoxide Detector around with you.

This model is very small and portable, allowing you to carry it with ease and keep it in a bag or even in your pocket. There is also a belt clip if this is something you would prefer. It has a reliable electrochemical sensor and can show specific levels if this is something you need to monitor.

It is very easy to operate with a simple interface to check the levels, and if portable is high on your priorities then this could be a good option.

What do we love it for?

  • Easy to operate.
  • Comes with a belt clip.
  • Reliable sensor.
  • Shows specific levels of CO in the air.

What were we disappointed with?

  • Not really suitable for keeping in one location. Doesn’t attach to wall or ceiling due to being portable.

First Alert 2-in-1 Z-Wave Wireless Smoke Detector & Carbon Monoxide AlarmBest Battery Operated Smoke And Carbon Monoxide Detector

  • Sensor: electrochemical
  • Power: battery-powered
  • Smoke detector: yes
  • Dimensions: 8 x 7 x 2.5 inches

Extra features: 7-year warranty; use with Nexia Home Intelligence, Ring Home Security, or other Z-Wave systems

We’ve named the First Alert 2-in-1 the best battery operated smoke and carbon monoxide detector. It is great for homes and creates a good balance between smoke and CO detection as well as compatibility with some smart home systems for that extra bonus of connectivity. All of this comes at a very reasonable price, too.

This is easy to use and can connect with other alarms in your home so that the alarms can go off together if required. It can also send you alerts to your mobile or even to an email account.

The detection comes via both a photoelectric and electrochemical sensors.

It is a good home carbon monoxide detector and installs very easily, the mounting ring attaches to the wall and the detector itself just clips in.

What stands out?

  • Connects to other alarms and some nest systems
  • Can alert mobiles and even send emails if the alarm goes off while you are away
  • Good value-for-money

What cons did we manage to find?

  • Some people have found it complicated to connect to their ring system or other smarthome functions
  • Battery life is not as good as some competitors
RELATED: 7 Most Reliable Smoke Detectors — Protect Your Loved Ones and Keep Your Home Safe
  • Sensor: not specified
  • Power: battery-powered
  • Smoke detector: no
  • Dimensions: 2.7 x 1.9 x 0.8 inches

Extra features: 1-year warranty; comes with 2 li-ion batteries

Detecting CO levels is important in any enclosed space, and this includes those you may travel in such as buses, aircraft, and even cars. This is our best travel carbon monoxide detector. Of course, in a vehicle you have the extra risk that can be presented as carbon monoxide can be a product of the engine. This can cause drivers to fatigue, headaches and far worse.

The Forensics detector has an extremely accurate sensor and you can set the alarm levels to be different. You may wish for a 9ppm or a 25ppm alarm. Both are possible with this detector.

The battery life is also excellent which is something you’ll find very handy considering the fact you will be using this product on-the-go. It can last 12 months with the same batteries.

For use within a vehicle, or other portable uses, this carbon monoxide detector is worth considering.

Why are we impressed?

  • Easy to use
  • Portable
  • Can last a full year on the same batteries
  • Multiple alarms depending on your preferences for ppm monitoring

What negatives must you be aware of?

  • The unit isn’t designed to show any CO level below 9ppm so you won’t see if there is background CO
  • Can’t be fitted to one fixed spot

Universal Security Instruments 10 Year Carbon Monoxide AlarmBest Battery Operated Carbon Monoxide Detector Under $50

  • Sensor: not specified
  • Power: battery-powered
  • Smoke detector: no
  • Dimensions: 2.2 x 5 x 5 inches

Extra features: 10-year service with 10-year warranty; comes with the required (sealed) battery; microprocessor ensures no nuisance alarms

This is a very good value carbon monoxide detector which can be fitted either on a wall or on a table top.

We’ve named it the best battery operated carbon monoxide detector in its price range and it is brilliant for those who just want to install something to protect them and then not give it too much thought from there forward.

The alarm can provide 10 years of protection on the same incredible battery. This is also an Alkaline battery which can be disposed of far more easily than lithium.

The smart alarm is designed to wake you up if something occurs in the middle of the night. It is also designed not to have any nuisance alarms which can be very annoying.

Whether you want to put this on your desktop, tabletop or mount it on the wall it is equally simple.

What are its best features?

  • Easy to mount and install
  • Carbon monoxide detector has a battery life of 10 years, maintenance-free
  • Small and compact design
  • Designed not to create nuisance false alarms

What could be improved?

  • No smart features
  • Battery is sealed so changing when the 10 years is up is tough
  • Doesn’t have a smoke detector built in

First Alert Plug-In Carbon Monoxide Detector CO600 Best Home Carbon Monoxide Detector

  • Sensor: electrochemical
  • Power: plug-in
  • Smoke detector: no
  • Dimensions: 8.5 x 6.8 x 2.8 inches

Extra features: 7-year warranty; 85 dB alarm; UL Listed

If you are looking for an easy-to-use and reliable home carbon monoxide detector then the First Alert Plug-In Carbon Monoxide Detector CO600 could be a good option. It is very much a “no-frills” product and though this doesn’t come with any extra features such as smoke detector or the ability to connect to any smart home network, it is perfect for those on a budget who just want a reliable and long lasting product.

You can rest assured that the first alert will do a suitable job for some time as the company have been confident enough to provide a 7-year warranty.

The sensor is electrochemical and this is powered by plugging into your mains supply. Should it need to alert you, a standard 85 dB alarm is perfect for waking you up and making sure you hear clearly.

What makes it special?

  • Easy to set up, plugs straight into a power supply
  • Reliable alarm which is easy to test with one button
  • Affordable
  • Comes with a long warranty

What cons did we find?

  • No additional features such as a smoke alarm
  • No backup battery system if the mains power fails
  • Doesn’t have the capability to join up to any smart home network
  • Sensor: not specified
  • Power: plug-in with battery backup
  • Smoke detector: no
  • Dimensions: 2.8 x 1.5 x 4.5 inches

Extra features: 7-year warranty; comes with 2 AA batteries; tamper-resistant; UL listed

Our budget choice is also the best tamper-proof option for carbon monoxide detectors, designed so that if children get to it they can’t easily and inadvertently change the settings or create a false alarm, and that if anyone deliberately tries to tamper this is much harder. This is one of the cheapest home carbon monoxide detectors that you can buy, but we still think a lot of it.

Considering the price this is a top rated carbon monoxide detector. If you’re on a budget, you don’t need to worry about your safety as a result of buying a more affordable option.

This has an excellent 7-years of warranty, and it works with mains power but also with AA batteries, this means that if anything goes wrong with your power supply then your batteries will kick in so you still have carbon monoxide detection.

If you need to test the alarm you can hit the single button to check that it is working. This is very simple.

Why are we impressed?

  • Extremely low price point for a decent CO detector
  • 7-year warranty as standard
  • Reliable alarm

What negatives must you be aware of?

  • No ability to connect to smart home features
  • Not as sturdily made as some of the more expensive options

Things to Consider

If you’ve looked through our list of the top carbon monoxide detectors on the market, you will see how many different types there are with different functionalities. It can be easy to assume they all do exactly the same job, but the truth is there is some variation on the market. Different products are designed with different consumers in mind, and we’ve created a buying guide to help you to establish which is going to be the best for you and your own needs (not to mention budget). The guide will help you to understand features as well as what you’re likely to have to spend.

Why it’s important to install a carbon monoxide detector

8 Highly Sensitive Carbon Monoxide Detectors to Secure Your Home or OfficeCarbon monoxide, commonly abbreviated to CO, is an extremely dangerous toxic gas. It is made when combustion is incomplete. Without a detector, you won’t know that it is being released, as it doesn’t have a smell or anything that you will notice. If you inhale it then the gas can get into the bloodstream and causes lack of oxygen to the brain. Sometimes the main symptoms are confused with the flu or other signs of illness. CO poisoning can make you disorientated, too, so it is hard to know what to do if you are exposed.

In some cases, CO poisoning can be fatal. This means that being able to detect it, act, and get out of the area is absolutely vital. For the sake of the cost of a detector, it is not worth any sort of risk.

Carbon monoxide exposure limits

The effect on health is not guaranteed between 1 and 70 ppm. In most cases, this won’t cause any symptoms. The maximum exposure to CO for an 8-hour workday is 35ppm. If levels reach 70 ppm and increase you may experience a headache, fatigue or nausea. High levels of 800ppm and over will result in severe symptoms, and even death within 2-3 hours.

Features to consider when choosing a carbon monoxide detector

As you can see from the information above, there is no point taking any risks with your carbon monoxide detector. In this section, we’re looking at the best features to consider when choosing the best carbon monoxide detector for you.

Type of sensor

Most of the best carbon monoxide detectors, including our editor’s choice model, use electrochemical sensors. These are gas detectors which reduce the target gas at an electrode and then measure the current, which shows the gas level. This is a very reliable form of sensor. The First Alert Dual-Power Carbon Monoxide Detector Alarm is an example of a product with this type of sensor.
Other types of sensors include metal oxide semiconductor and biomimetic types.

Power source

8 Highly Sensitive Carbon Monoxide Detectors to Secure Your Home or OfficeThe sensors may need power, and alarms will definitely need some form of power. There are different ways that power can be provided. Some products have exceptionally long batteries, for instance, the Universal Security Instruments 10 Year Carbon Monoxide Alarm will last for an incredible 10 years without needing a new battery.

You can buy both battery and hardwired smoke and carbon monoxide detectors.

Some items plug straight into mains power, which is a good way to power your detector. If you do go for this option, try and get one with a backup battery system so it will even work if your power fails.
The Kidde Tamper Resistant Plug-In Carbon Monoxide Detector Alarm is an example of this.

Does it come with a built-in smoke detector?

Some of the products have been designed to have both a smoke detector and a carbon monoxide detector within the same casing. This has its pros and cons, but is a good way to save money and ensures that you can test for both in the same product and improve the safety of your home. Products such as the First Alert 2-in-1 Z-Wave Wireless Smoke Detector & Carbon Monoxide Alarm include both at great value for money.

Smart functionality

We truly live in the age of smart technology. It may be that your product can connect to Nest or Alexa. Our editor’s choice, the Nest Protect, is one such example of a product with this capability. It is not vital that your CO detector can do this but it is a good safety feature to get alerts on your phone and connect to other types of alarms and detectors, for example.

Is it UL-listed?

UL listing is an independent testing system which makes sure that your detector or alarm has been approved for its safety of use in the USA. This is a good way to ensure that the product you buy has been independently tested and approved.

CO measurement range and accuracy

8 Highly Sensitive Carbon Monoxide Detectors to Secure Your Home or OfficeMost of the products have petty good accuracy levels. All are accurate enough to tell you when your levels have risen to a point where you may find yourself in danger. Some needs, such as industrial uses of carbon monoxide detectors, mean that a measurement range and accuracy need to be specified. The PPM ratings on your carbon monoxide detector will be listed.

Operating temperature

These products also have optimal temperatures at which they work. If you are using your device in a working environment for instance and the temperature is high, it might be worth checking this to see if your detector will still be performing at its premium level.

Dimensions and portability

The dimensions of your chosen CO detector will determine the best place to install it. Larger CO detectors won’t be very good as a portable carbon monoxide detector.

Smaller, more compact models will be great for things like industrial uses like building sites.
These smaller units are not suitable home carbon monoxide detectors. We’ve found the UEi Test Instruments CO71A Carbon Monoxide Detector to be the best portable CO detector. It is pocket-sized and great for taking out and about.

CO detector installation and maintenance

Ideally, you should have CO detectors in each room of your home. This ensures that the safety has been thoroughly considered. The ideal place to install is five feet from the ground. The only maintenance which is required is regular testing to make sure the battery is still working. This usually only involves pressing one button and then the alarm will be set off as a test.


There are pros and cons to CO detectors with smoke detectors. It is a convenient way to do things, but the ideal installation for both is in different places, meaning some compromise will be made. A smoke alarm should ideally be installed on the ceiling, whereas a CO alarm should be installed about 5 feet from floor level.

The majority of the time, these products can be installed with some simple DIY, so you shouldn’t need a professional.

You should have a carbon monoxide detector in every room ideally, but this is not always practical. If you cannot install one in every room, make sure there is one on every floor of your home.

Our Verdict

Our highest rated CO monitor at 9.9/10 is the Nest Protect Smoke and CO Alarm. The way that this connects to your smart home and has smart features such as lights gives an added bonus to users.

The First Alert Dual-Power Carbon Monoxide Detector Alarm is our second choice at 9.8, it is very safety conscious as it has a backup battery system if the mains fails.

Third on our list is the UEi Test Instruments CO71A Carbon Monoxide Detector, which is the best portable option out there and very easily maneuverable, making it great for professional monitoring of CO levels.

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