Top 10 Best CO2 Monitors
for June 2023

The GZAIR Model 1 CO2&HygroMometer is a handy way to keep tabs on your home's indoor air quality. Just place it near a window, and it'll monitor the levels of carbon dioxide (CO2) and humidity (H). This can alert you if the levels are high, or allow you to adjust them to keep the air healthy. The GZAIR Model 1 is an easy-to-use, affordable option that tracks CO2, temperature, and humidity. The unit is small enough to fit on a shelf or desk, and it's battery-powered, so you'll never need to worry about replacing a cord. The GZAIR Model 1 can also log readings for up to 7 days, or 1,000 readings, so you can track changes over time. This detector can also be used outdoors to track CO2 levels, or in enclosed spaces like basements, garages, or warehouses. We'll note that this detector isn't meant for continuous monitoring, as it can't detect CO2 levels as low as 0 parts per million (ppm). The remote isn't as easy to use as we'd like, but in general, this detector is easy to use, accurate, and provides you with the information you need to keep your home air healthy.

The GZAIR CO2 meter is a handy little gadget that we recommend measuring CO2 levels in your home, especially if you have plants, pets, or a chronic respiratory condition. It measures CO2 levels, and also measures the temperature, relative humidity, and relative air speed (in a different unit, BTU). At each level, the gauge can glow green, orange, or red to indicate a healthy range, over or under the recommended range for your environment. Lite and compact, it easily fits in a jar or on your desk. It also stores up to three 15-minute readings, which you can view through a backlit LCD. Although its accuracy is very good overall, the CO2 range is relatively small (0.0001 to 100,000 parts per million, or ppm). But keep in mind that most CO2 meters don't measure anywhere near that range, so this is a lot better than most.

Although it looks like a glorified CO2 pen, the CO2Meter is a reliable, accurate, and reasonably-priced monitor for CO2 levels, perfect for users who want to protect their employees or customers from unhealthy levels of CO2, or just test their own air quality. The CO2Meter not only has a 3-level CO2 LED readout (up to 900ppm), it also has an alarm level indicator LED (all LEDs can be turned off), and the unit has an on-board 4-digit digital readout. The manufacturer's specs for the CO2 meter are for 120V, but the unit's connection port is USB, which can be plugged into any power source. For tracing sources of high CO2, the CO2Meter is also equipped with a laser pointer. The CO2Meter is also compatible with optional V2 and V3 USB adapters, which extend its range. The CO2Meter is compact, portable, and simple to use. It's faster (and more accurate) than a traditional CO2 meter, and it's less expensive than most portable CO2 monitors.

We bought a few CO2 monitors over the last few years, and were disappointed by how much data they logged and how many false alarms they had. They also didn't track temperature or humidity. The GZAIR model 1S indoor carbon dioxide detector doesn't suffer from those problems. It uses an NDIR sensor that measures the infrared absorption in air samples. It's accurate, fast, and easy to read. The display is large and has 3 buttons, one to turn the alarm on and off, one to switch between modes (human and plant), and the third to cycle through the data. The alarm will sound when the CO2 level reaches 1,000 ppm, and is loud enough to be heard on the covered patio.

The Dr.meter MAX CO2 Monitor and Data Logger isn't the most stylish or user-friendly data logger, but it gets the job done. Testers liked the large LCD display and simple controls, but the best feature of the Dr.meter MAX is the built-in data logging software. With it, you can plot and compare data from up to 100 sensors, then analyze them by PC or Mac. It works with most popular sensors. Our only complaint is that it doesn't scale the data to your units automatically, but you can have that fixed by installing the free DrMeter calibration app, then typing in the unit you're using. For its small size, the Dr.meter MAX also offers good accuracy. We found it slightly on the low side for CO2 (compared with the more professional-grade Co2 Meter). And for temperature and humidity, it was good to excellent in most situations. That makes it a good choice for most DIY and hobby purposes. It also offers excellent battery life, not needing a recharge after 25 hours of continuous recording.

This air quality monitor is a very useful tool that combines a highly accurate air quality sensor with an attractive, mostly modern-looking design. Its large blue OLED screen is both easy to read and rather bold, and the unit has a fairly long battery life — it can run for 24 hours when the display is off and 8 hours when the display is on — though at 8 hours it feels less like you're getting as much as you could. Low-cost, small, and portable, this monitor is a good choice for anyone wanting to gauge the air quality in their home or office, and it eliminates the need for a standalone sensor. Its only weakness is that, while it's accurate enough to use as a guide to measure improvements, it doesn't physically move from one room to another — it can't, for example, alert you to increased pollution if you bring home a new pet or move furniture around the home or office. For those reasons, it's a little heavier than we'd like, and we wish Temtop had included a small carrying bag.

This CO2 sensor from Compared with this competition, it's ideal for those looking for a low-cost and portable way to monitor indoor carbon dioxide levels. It measures 0.5-9999.99 parts per million (ppm) while 0.2-2000 ppm can maintain a high accuracy. And it's able to issue an audible alert whenever it reaches the preset level, and it's simple to set up and to use. Readings last only 15 minutes or for a full 8 hours, depending on which you choose, and it requires 4 AAA batteries.

The Temtop M2000 is a great value for a home indoor air quality monitor. It has a good selection of sensors (carbon dioxide, formaldehyde, temperature and humidity), a continuously updated OLED display, and adjustable alarm sounds. The air quality sensors are accurate, and the volcano-style integrated digital imprinting makes for easy data reading. It's easy to set up, and the software is easy to use; we especially like the color-coded report and alert functions. The Temtop M2000's big drawback is its price, which is among the most expensive monitors we tested. It's still a good value if you're concerned about indoor air quality, though, and we've never seen a cleaner-looking display panel than this one.

The Air Quality Monitor is the most accurate and easy-to-use CO2 monitor we could find, and it's accurate to within 0.3%. The Air Quality Monitor is attractively designed, has a crisp color display, and it measures both CO2 and temperature. It has a built-in fan, so it can measure CO2 without fans or sensors, and it does this more accurately than other CO2 monitors. This monitor is also powerful and durable, with an IP66 rating, so it should be fine for outdoor use. It's portable enough to be used on camping trips, but it's too big and heavy to be carried around in your pocket. The unit is also expensive, and it requires an extra recharger for long-term use. But it's a lot cheaper than the home CO2 detectors, and the Air Quality Monitor does a lot more. We like the real-time monitoring and touch screen interface, which is intuitive and easy to use. We also like the 2-year warranty and lifetime customer support. This monitor has lots of pluses, but one significant drawback is that it's currently not compatible with Apple's HomeKit, so you can't control it remotely with Siri. If you're an AirPod user, this might not matter to you.

This has certainly been the best desktop CO2 monitor we've ever tested. The backlit display is readable from across the room, and the data is graphed nicely. Despite its bulky exterior, the Hydrofarm APCEM2 is light and easy to mount on a standard tabletop. It has a range of sensors to accommodate different growing conditions, so it's easy to adapt to your specific growing setup. Again, we used one of the default settings, but for hydroponic growing, you'll want to adjust the CO2 levels to match your own system: we adjusted the input to give the unit a reading from the plant's canopy, so a more bottom-up approach might be better for plants growing in soil. We think this is the best desktop CO2 monitor we've tested, and it's just as well made as other countertop gadgets we've tested, such as the Grofit System. It's not cheap, but it's money well spent.