Lowest priceRecorded by the Android app

SwitchBot Meter Pro (CO₂ Monitor)

The lowest-priced true CO₂ monitor we found. Keep it on USB power so it updates every minute.

About $50–$70checked October 2026

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Photo: SwitchBot

±(50 ppm + 5%)CO₂ accuracy, as the maker states it
Listens overnightWith the Android app; type it on iPhone
Not statedSelf-calibration
Plug it inPlug it in (USB) for minute-by-minute readings

At a glance

In its favour: The Android app records nights while your phone listensNew: tested with simulated broadcasts so farOn iPhone, type the night’s high each morning.
Plain fact: Plug it in (USB) for minute-by-minute readings
Not stated by the maker: Self-calibration not stated by the maker
Not stated by the maker: Altitude correction not stated
Worth knowing: Get the CO₂ version: the plain Meter Pro has no CO₂ sensor

With HouseExhale

The app looks at your bedroom’s CO₂ across the night and checks it against the 800 ppm goal. Here’s how this monitor’s nights get in.

With the Android app

With the Android app, your phone listens to it overnight and saves a reading every minute. Keep the phone in the room, charging, and the monitor on USB power.
New in the app: tested with simulated broadcasts, not yet with a real monitor overnight.

On iPhone or in a browser

On iPhone, HouseExhale can’t read it directly. Each morning, type the night’s high from the SwitchBot app, or try importing its export.

There’s no iPhone app yet. Use HouseExhale in Safari and add it to your home screen.

Setting it up

Install the SwitchBot app from your phone’s app store.
Tap + to add a device and choose Meter Pro (CO₂).
Keep your phone nearby while it pairs over Bluetooth.
Plug it into USB power for your checks.
On USB power it updates CO₂ about every minute. On batteries it only updates about every 30 minutes, which gives a rough picture of the night at best.
You may need your own USB wall adapter.

The box and screen should say CO₂. The plain Meter Pro (no CO₂) only measures temperature and humidity.

Finding last night’s high

Open the meter in the SwitchBot app, tap the CO₂ chart and look at last night. Note the highest point while people were asleep.

Importing its export

Open the meter in the SwitchBot app.
Open its settings (gear icon).
Scroll below the graphs and tap Export Data.
Save or share the CSV file, then choose it here.

SwitchBot documents CSV export for its meters. We haven’t yet confirmed the CO₂ column on a real export, so the app checks your file before saving.

Where to put it: about head height, at least 2 ft from anyone’s face, away from windows, doors and vents, and in the same spot every night. More on placement

Calibrating it

Not stated by the maker: Self-calibration not stated by the makerNot stated by the maker

Let the meter settle outdoors in the shade for 15 to 30 minutes first (our advice; SwitchBot’s minimum is 1 minute), pressing the top button now and then to refresh the reading. Then in the SwitchBot app open the meter, tap the gear icon, Calibrate, CO₂ Monitor. It takes about 5 minutes; keep your phone nearby and don’t move the meter. SwitchBot recommends battery power while calibrating.

In the SwitchBot app (version 9.1 or newer): put it outdoors in a well-ventilated spot for a minute, then gear icon, then Calibrate, then CO2 Monitor. It takes 5 minutes; stay within Bluetooth range and don’t move it. SwitchBot suggests calibrating if it reads above 500 ppm in fresh air.

Outdoor air is about 425 ppm. Outside in the shade, a good monitor settles between about 400 and 450 within 15 to 30 minutes. Many monitors treat fresh air as 400, so 400 to 420 is normal. Can I trust my monitor?

Specs

Model: W4900010
Sensor and accuracy: True CO₂ (NDIR), ±(50 ppm + 5%); SwitchBot doesn’t name the sensor module
Self-calibration: Not stated by the maker
Corrects for altitude: Not stated by the maker
Also measures: Temperature and humidity; the screen also shows the time, date and a comfort level
CO₂ range: 400–9,999 ppm
How often it updates: On batteries the CO₂ reading updates every 30 minutes, and that can’t be changed. On USB power it switches to every minute, and can be changed in the app (gear icon, then Panel Display, then Data Update Interval, then CO2); SwitchBot warns that faster than once a minute keeps the sensor running and can warm it slightly. The top button or the app’s Refresh button forces an update. It keeps 38 days on the monitor, and 2 years in the app’s cloud with a SwitchBot Hub.
Power: USB-C or two AA batteries. On batteries the CO₂ reading updates only every 30 minutes; on USB, every minute.
Screen: 3.6-inch display, not backlit
History: 38 days on the monitor; the SwitchBot app exports a CSV (not yet confirmed with CO₂ on a real file)
App: SwitchBot app, for iPhone (iOS 15.1 or later) and Android
Exports a CSV: Documented; not yet confirmed on a real file
Connects by: Bluetooth (SwitchBot gives 120 m in the open). You need a SwitchBot Hub, sold separately, for phone alerts, cloud history and data export, viewing it away from home, and voice assistants. The SwitchBot app needs you to log in.
Alarm: A buzzer sounds and the numbers flash on screen when CO₂ (or temperature or humidity) passes a level you set in the app. SwitchBot’s app release notes say CO₂ alarm levels can go up to 9,999 ppm. No default level found. Phone notifications need a hub.
Smart home: SwitchBot lists Alexa, Google Home, SmartThings, IFTTT and Siri Shortcuts; a reviewer notes these need a SwitchBot hub. Home Assistant: the official SwitchBot integration reads CO₂ locally over Bluetooth. Matter: listed through SwitchBot Hub 2, but neither SwitchBot nor Home Assistant says CO₂ comes through, and a November 2024 review found it didn’t. Apple Home (HomeKit) isn’t listed.
Size: 92 × 79 × 25 mm (3.6 × 3.1 × 0.98 in)
Weight: 154 g, with batteries
Works in: No operating range given. SwitchBot recommends using its batteries between 5 and 45 °C. It measures −20 to 80 °C and 0–99% humidity.
In the box: The monitor with two AA batteries and a USB-A to USB-C cable; no power adapter
Warranty: Sources disagree: SwitchBot’s EU store says 2 years; Ameridroid, a US seller, says 1 year. The SwitchBot product page opened doesn’t say.

Specs from the maker’s own pages, checked October 12 and October 17, 2026. “Not stated by the maker” means no maker page we could open says.

Turning ventilation up

Home Assistant’s SwitchBot integration reads its CO₂ over Bluetooth, with no cloud. SwitchBot’s own app can also use its CO₂ level to press a SwitchBot Bot, with a SwitchBot hub. Home Assistant: SwitchBot integration (docs source)

With a smart-home relay on a ventilator’s high-speed input, that reading can turn an HRV or ERV up at 750 ppm and back down at 650. Ventilator makers don’t document this, so check your unit’s manual first, and keep to low-voltage inputs.

CO₂ controls · Make the system you have turn up by itself

Before you buy

Worth knowing: Get the CO₂ version: the plain Meter Pro has no CO₂ sensor
Plain fact: About $50–$70 before tax and shipping$69.99 at SwitchBot’s US store, which adds shipping under $99. Sale prices from $49.95 to $59.48 at Ameridroid and Amazon in October.
Plain fact: New in the Android appTested with simulated broadcasts, not yet with a real monitor overnight.

About $50–$70, checked October 2026. Prices change often; we checked at the maker’s store and large US retailers. Any monitor that measures true CO₂ works with HouseExhale, and one is enough: move it between rooms.

SwitchBot Meter Pro (CO₂ Monitor) at SwitchBot (opens in a new tab)

Compare it

The monitors closest to it in price.

Qingping CO₂ & Temp & RH Monitor
About $70
Rechargeable, with 24-hour and 30-day graphs in the Qingping IoT app. Plug it in overnight so it updates often.
INKBIRD IAM-T2 (Bluetooth version)
About $70–$80
A rechargeable monitor that runs about 60 days on a charge. Get the Bluetooth version.