Last updated: 16/10/2022

Welcome to our big CO2 detector test 2022. Here we present all the CO2 detectors we have tested in detail. We have compiled detailed background information and added a summary of customer reviews on the web.

We would like to make your purchase decision easier and help you find the best CO2 detector for you.

You will also find answers to frequently asked questions in our guide. If available, we also offer you interesting test videos. Furthermore, you will also find some important information on this page that you should definitely pay attention to if you want to buy a CO2 detector.


  • A CO2 detector measures the amount of carbon dioxide in the air and sounds an alarm as soon as a certain concentration is reached.
  • Basically, a certain amount of carbon dioxide in the air (approx. 500-1000 ppm) is normal and harmless. However, at higher levels (2500-3000 ppm and above), headaches or shortness of breath may occur.
  • In closed rooms, the air deteriorates imperceptibly. A CO2 detector alerts you to too high a concentration of carbon dioxide, reminds you to ventilate and ensures that you are spared annoying headaches due to carbon dioxide.

The Best CO Detector: Our Picks

Guide: Questions you should ask yourself before buying a CO2 detector

What is a CO2 detector?

Carbon dioxide is the chemical compound of carbon and oxygen. A CO2 detector is therefore a device that controls the concentration of carbon dioxide indoors with the help of a sensor.

When a certain level of carbon dioxide is exceeded, the CO2 detector sounds an alarm. In this way, you are optimally protected against carbon dioxide poisoning and can better control the quality of the indoor air.


CO2 detectors are only suitable for indoor use. To avoid damage, you should never use CO2 detectors outdoors.
(Image source: / Deborah Cortelazzi)

How is carbon dioxide produced and why should you measure it?

Carbon dioxide is a compound made up of carbon and oxygen. About 0.04 per cent of our air is made up of carbon dioxide. Carbon dioxide is produced, for example, when fossil fuels such as coal, natural gas or petroleum are burned.

But carbon dioxide can also be produced by cellular respiration in plants, animals or humans. A single person alone exhales an average of about 15-20 litres of air per hour during a sedentary activity, thus adding more than a hundred times the amount of CO2 to the air.

The amount of carbon dioxide emitted per day by a single person is therefore equivalent to the amount emitted by a small car travelling ten kilometres.

Carbon dioxide in rooms is not dangerous for the environment, but in too high a concentration it impairs our well-being. For an optimal indoor climate, especially in rooms where many people are present, a CO2 detector is definitely an advantage.

For whom is a CO2 detector suitable?

A CO2 detector is basically suitable for everyone. Unlike smoke detectors, however, there is no obligation to install a CO2 detector in private households.

In the following commercial sectors/locations, the installation of a CO2 detector is particularly important, as larger amounts of CO2 can accumulate here and this represents a considerable health hazard:

  • Breweries
  • Gastronomy
  • Wine cellars
  • Greenhouses
  • Feed silos

With a CO2 detector you can also save energy in your own home. Many households have demand-controlled ventilation. You can adjust this according to the measured values of the CO2 detector. In this way, you always ventilate when the carbon dioxide content has reached a certain threshold.

Did you know that especially residents of new and well-insulated rooms should keep a close eye on the CO2 concentration?

Due to the reduced exchange with fresh outside air, a larger amount of carbon dioxide is produced very quickly in closed, well-insulated rooms.

Up to what CO2 level is air considered clean?

The concentration of carbon dioxide measured in ppm (parts per million) is very closely related to the quality of the air. In the table below we give you an overview of the CO2 values and the resulting air quality.

CO2 concentration Air quality/possible symptoms
Up to 300 ppm Very fresh air
Up to 1000 ppm Acceptable room air (ventilation becomes necessary)
Up to 1500 ppm Maximum value for acceptable room air (ventilation becomes urgently necessary
Up to 2500 ppm Headaches may occur
Up to 5000 ppm Breathing difficulties may occur

You can use 1000 ppm as a simple guideline. The carbon dioxide concentration in the room air should not exceed this value.

What is the difference between a CO2 detector and a CO detector?

In addition to carbon dioxide measuring devices, a CO detector is also useful for checking the air quality. A CO detector alerts you as soon as the carbon monoxide concentration in the room exceeds a certain level that could be harmful to you.

Carbon monoxide is a colourless, poisonous and odourless gas that is produced when substances containing carbon are burnt. Even low concentrations of carbon monoxide can lead to carbon monoxide poisoning without you noticing.

We recommend that you use an additional CO detector in addition to a CO2 detector to check the air quality.

Note that a CO detector and a CO2 detector measure different gases. They are two completely different devices that must be purchased separately.

Unlike CO detectors, which are mounted on the ceiling like smoke detectors, you should place a CO2 detector near the floor. This makes sense because the gas carbon dioxide is heavier than air and is deposited on the floor.

What does a CO2 detector cost?

Basically, there is a wide range of prices between CO2 detectors. Depending on the manufacturer, supplier or type of device, the prices can vary greatly for one and the same model.

An online price comparison is highly recommended

CO2 detectors cost between 70 and 200 euros. Portable CO2 detectors are the cheapest. Some models can be bought for as little as 70 euros. Multifunctional or recording CO2 detectors are usually considerably more expensive. Here, the price is approximately between 130 and 200 euros.

In the following table, we have summarised the prices for the different models of CO2 detectors:

Model Price
Multifunctional CO2 detector approx. 150 – 200 €
Recording CO2 detector approx. 130 – 200 €
Portable CO2 detector approx. 70 – 90 €

How many CO2 detectors should you buy?

Basically, CO2 detectors make sense in places where many people spend long periods of time. For example, in the living room, classrooms and offices.

Air quality should also play a major role in children’s rooms. Here, it is advisable to install a CO2 detector that you can connect to an app on your mobile phone. This way you can track the values anywhere and at any time.


An increased concentration of carbon dioxide also means an increased risk of infection from colds, flu or fever. Checking the CO2 level and airing the room regularly can minimise the risk of infection.
(Image source: / Online Marketing)

Decision: What types of CO2 detectors are there and which is the right one for you?

If you want to get a CO2 detector, there are three models you can choose between:

  • Multifunctional CO2 detector
  • Recording CO2 detector
  • Portable CO2 detector

What are the advantages and disadvantages of each model?

Multifunctional CO2 detector

Multifunctional CO2 detectors are not only limited to measuring carbon dioxide, but also show you additional values such as temperature or humidity. Some of these models also have a time and alarm function.

However, these devices only cover a CO2 content of up to 5000 ppm. This is, however, completely sufficient for living and sleeping areas, schools or offices. The measuring rhythm is also somewhat slower with this variant of a CO2 detector than with other models.

  • Multifunctional
  • Mostly configurable alarm
  • Versatile
  • Slow measuring rhythm
  • Measuring range only goes up to 5000 ppm
  • No recording function

Recording CO2 detector

If an exact overview of the development of the CO2 concentration is needed, one should take a look at recording CO2 detectors. These models store the measured CO2 content of the room air and show the progression of the air quality on their display.

Recording CO2 detectors usually cover a larger measuring range than multifunctional devices and have a faster measuring rhythm. They are therefore somewhat more expensive to purchase.

The purchase of a recording CO2 detector makes sense primarily where precise and regular control of the CO2 content is required. Examples of this are cellars with wood gasification boilers or the ownership of a pellet heating system.

  • Particularly precise measurement (fast measuring rhythm)
  • Large measuring range (up to 10000 ppm)
  • Mostly configurable alarm
  • Very high-priced

Portable CO2 detector

Especially if several rooms are to be checked for CO2 concentration, the C02 detector powered by batteries or rechargeable batteries is a good choice. A portable CO2 detector is also the perfect companion for irregular checks of rooms or in caravans / mobile homes.

Portable CO2 detectors are also characterised by a particularly fast measuring rhythm and are significantly cheaper to purchase than other models of CO2 detectors.

  • Mobile use
  • Large measuring range (up to 10000 ppm)
  • Low purchase price
  • Only works with accessories (battery or rechargeable battery)
  • Does not have a recording function

Buying criteria: You can compare and evaluate CO2 detectors based on these factors

LED display

With the help of an LED display, you can see directly at first glance and even from a distance how the respective CO2 value is.

Many models now have an LED traffic light display. This gives you a direct and accurate impression of the CO2 concentration in the room air. We therefore recommend that you buy a CO2 detector with LED display as well as an LED traffic light display.

Evaluation of the measured values via app

Various CO2 detectors now offer this function. This is practical if you want to check the CO2 values in your home while on the road. It can also be an advantage during longer holidays to be able to take a look at the CO2 values at home.

This device is really worthwhile especially for houses with pellet heating or other sources of danger for increased CO2 emissions.

Recording function

With a recording function, you can see the values of the last 24 hours as well as the current maximum and minimum values of the CO2 concentration in the room air.

This makes it easier to find out how often you should ventilate and how long it takes for the carbon dioxide level to return to normal. Especially in buildings where there are many people, a CO2 detector with a recording function can provide a great deal of information about optimal ventilation.

Configurable alarm

A configurable, user-defined alarm is another purchase criterion you should think about before buying a CO2 detector.

With the help of a configurable alarm, you can set your own alarm values and know at any time and, above all, in good time how the carbon dioxide content of the air of the corresponding interior is.

If the CO2 detector is connected to the ventilation system, you can ensure optimal ventilation around the clock, even if you are not on site.

Measuring range / measuring rhythm

Measuring range and measuring rhythm are also important if you are considering buying a CO2 detector. As a rule, CO2 detectors have either a measuring range up to 5000 ppm or a measuring range up to 10000 ppm.

Depending on the place of use, you need to weigh up how accurate the measurement results should be. This is where the measurement frequency comes into play. The more frequent the measurements, the more accurate the results.

For exact measurement results, especially in buildings where many people are present or for professional use in the catering industry or agriculture, we recommend a CO2 detector with a large measurement range and a fast measurement rhythm.

Facts worth knowing about CO2 detectors

What should I do if the CO2 detector sounds the alarm?

First of all, you should quickly open the window and ventilate well. This usually solves the problem of too high a concentration of carbon dioxide in the room air.

However, to prevent this, you should ventilate regularly and, above all, properly. We recommend that you fully open the windows 3-4 times a day for about 10 minutes, regardless of the season.


“Proper ventilation prevents not only a high carbon dioxide concentration, but also mould growth, for example. For the sake of your health, you should ensure that you have enough fresh air in your home, even in winter.
(Image source: / Luisa Guimarães)

Can I also use a CO2 detector as a fire detector?

No, CO2 detectors and fire or smoke detectors have different functions because they work with different sensors. A CO2 detector measures the carbon dioxide content and displays the corresponding value.

A smoke or fire detector, on the other hand, sounds an alarm as soon as smoke is detected.

In the following video you will find more information about installing smoke detectors.

Picture source: Raths/