CO2 Monitors
A CO2 monitor shows when a room needs fresh air. Outdoor air is about 420 ppm, and indoor levels climb as people breathe in a closed room. Many ventilation guides use about 1,000 ppm as a practical sign to open a window or run ventilation, and readings above 1,500 to 2,000 ppm indicate a stuffy, under-ventilated space.
What to compare
- Sensor: NDIR (non-dispersive infrared) measures CO2 directly. Avoid devices showing only "eCO2."
- Calibration: automatic baseline calibration or manual outdoor calibration keeps readings accurate.
- Display: e-ink screens are easy to read and save battery.
- Alarm thresholds: an audible or visual alert at a level you choose.
- Battery life and logging: some run months on batteries and store history.
Choose Portable CO2 Monitors for travel, classrooms and offices, or CO2 Monitors for Home for bedrooms and living spaces.
FAQs
What is a good CO2 level indoors?
Outdoor air is around 420 ppm. Indoors, levels under about 800 to 1,000 ppm generally indicate good ventilation. Many guides treat 1,000 ppm as a sign to bring in fresh air, while 1,500 to 2,000 ppm or more signals a stuffy, poorly ventilated room. CO2 mainly indicates how much fresh air a space gets.
Is a CO2 monitor the same as a carbon monoxide detector?
No. Carbon dioxide (CO2) monitors measure ventilation, while carbon monoxide (CO) detectors are life-safety alarms for a poisonous gas from fuel-burning appliances. A CO2 monitor does not detect carbon monoxide. Every home with fuel-burning appliances or an attached garage should have UL-listed CO alarms.
Why does CO2 go up in my bedroom at night?
Each person exhales CO2 while sleeping, and with the door and windows closed, little fresh air replaces it. Readings of 1,500 ppm or more by morning are common in small bedrooms. Leaving the door open, cracking a window or running ventilation lowers it.