How to Choose CO2 Sensor?

 

ATO.com brings you this practical guide: When buying a CO2 sensor, focus on 5 key features: measurement range, accuracy, sensor type, output interface, and environment. Choose NDIR (non-dispersive infrared) CO2 sensors for reliability. For most indoor uses, a 0–5,000 ppm range is enough. Look for accuracy within ±50 ppm or ±(50 ppm + 3% of reading). DIY users should pick UART or I2C interfaces; industrial users pick RS485. Finally, check your environment – greenhouses need humidity protection, outdoors need waterproofing.

Read on for details, product examples, and a 30-second comparison table in last appendix.

CO₂ Sensor Measurement Range (0-5000ppm to 10% Vol)

Will it work for my space?

CO₂ concentration affects humans and plants directly:

• 400 ppm – Normal outdoor air
• >5,000 ppm – May cause discomfort or lack of oxygen

Choose based on your use:

Use Case	Recommended Range
Indoor air quality monitoring	0–5,000 ppm
Industrial or special applications	0–10,000 ppm or higher (e.g., 10% VOL)

If you want wide coverage and all-in-one monitoring, the ATO-GS-CO2-D622 transmitter is a good choice ($163.82).

It can measure up to 50,000 ppm, has a strong and durable housing, and supports RS485 communication, making it suitable for long-distance wiring and easy system integration.

CO₂ Sensor Accuracy (±50ppm vs ±30ppm)

Can I trust the numbers? Accuracy tells you how close the reading is to reality.

Example: True CO₂ = 1,000 ppm. A CO₂ sensor with ±50 ppm accuracy will show 950–1,050 ppm – perfectly fine for most home use.

Good for home/office: ±(50 ppm + 3% of reading) or better

Excellent: ±30 ppm + 3% of reading

CO₂ Sensor Type (NDIR vs PAS vs Electrochemical)

• If you just want something simple:

If you're thinking, “I just want a CO₂ sensor to keep my plants from dying,” then the ATO-GS-CO2-Z19C is a great choice.

It’s good for indoor use or small potted plants. It works well even in humid air (0–95% RH) and isn’t easily affected by moisture. It’s perfect for a room or a closed balcony, and it costs just a little over $100.

• If you have a large greenhouse:

If you’re saying, “Hey, I don’t just have a few plants—I have a greenhouse as big as a football field,” then go for the ATO-ICDS-Z16.

• Fast response: Reaches 90% of the real CO₂ level in under 30 seconds
• Quick start: Only needs 10 seconds to warm up
• Wide range: Can measure up to 150,000 ppm
• Easy to use: Supports UART and PWM for simple integration

Don’t overthink it—this one is built for bigger jobs and gets great reviews.

CO₂ Sensor Type (NDIR vs PAS vs Electrochemical)

What’s inside matters?

NDIR (Non-Dispersive Infrared)

The standard choice. Reliable, stable, works for buildings, farms, and safety.

PAS (Photoacoustic)

Newer, smaller, uses less power. Good for wearables.

Thermal conductivity / Electrochemical

For special high-concentration or low-cost needs, but less accurate and shorter life.

Verdict: Stick with NDIR unless you have a specific reason not to.

CO₂ Sensor Output Interface (UART, I2C, RS485)

How do I connect it?

Match the output to your system

Your Setup	Best Output
Arduino / ESP / Raspberry Pi	UART or I2C (easiest to code)
Read voltage directly	Analog voltage (e.g., 0.4–2V)
Simple alarm trigger	Relay output
Industrial system / long distance	RS485 ModBus

DIY reminder: UART and I2C are your friends

If you’re just getting started with DIY, here’s a popular and reliable option we recommend: the ATO-ICDS-Z14A.

For beginners, we don’t suggest buying something too expensive right away. The ATO-ICDS-Z14A is affordable and still performs well:

• Warm-up time: about 1 minute
• Response time: T90 < 120 seconds
• Low power use: < 40 mA

It offers both UART/PWM digital output and a 0.4–2V analog voltage output, giving you flexible ways to read data. It also helps avoid inaccurate readings that could affect your greenhouse result.

Environment

Will it survive?A great CO₂ transmitters fails if the environment is wrong. Ask yourself:

• Temperature range (e.g., -10°C to 50°C)?
• High humidity (greenhouse, basement)?
• Dust or corrosive gases?
• Outdoor use (needs IP65/IP67 waterproof)?

Rule of thumb: Match the carbon dioxide detector to your environment first, then compare specs.

• If is needed in Greenhouse, then choose high-humidity resistant model.
• If is needed in Factory, then dust-proof + vibration resistant
• Outdoor → waterproof + UV resistant

For harsh conditions (dust, water spray, explosive gas), look for IP66 and explosion-proof certifications. 

If the environment you need to monitor is very harsh, your priorities should change. Here’s a simple and clear way to choose the right carbon dioxide sensor:

For harsh environments, follow this order:

1. Check the environment first
   Is it high humidity, corrosive, or explosive? These conditions can affect CO₂ monitor performance and safety.
2. Choose certified protection
   Pick models with protective or explosion-proof certifications. This ensures safe use in dangerous areas.
3. Estimate the highest CO₂ level
   Know the maximum gas concentration in your environment before choosing a sensor.
4. Match the measurement range
   Make sure the sensor’s range fully covers your expected gas levels.
5. Compare prices last
   After safety and performance are confirmed, then choose the most cost-effective option.This way, you focus on safety and reliability first, then cost.

If you need to deal with dust and water spray in enclosed spaces, here’s our top product: GD200-CO2.

Measurement method	NDIR (Non-Dispersive Infrared)
Target gas	CO₂ (carbon dioxide)
Measurement range	0–100% Vol, or optional 0–50,000 ppm
Accuracy	1 ppm (ppm range), 0.01% Vol (Vol range)
Fast response	T90 < 10 seconds
Zero drift:	≤ ±1% F.S. per year
Warm-up time	3 minutes
Protection rating	IP66
Explosion-proof rating	II 2G Ex ia IIC T4 Ga
Humidity range	0–95% RH (non-condensing)

It has an IP66 protection rating, so it can handle dust and strong water spray. It also comes with a professional explosion-proof certification, helping ensure safety and compliance.

Its measurement range goes from ppm levels up to 100% VOL, so it can cover almost all extreme concentration situations.

In addition, the built-in pump sampling system makes it ideal for testing in closed or hard-to-reach spaces where people cannot easily enter.

Summary

Once you understand these 5 key points, it’s easy to choose the right CO2 sensor. If you’re still unsure which one fits your needs, you can contact our engineers for free help. Or just check these four specs on the product page: measurement range, accuracy, output interface, and working environment —that will usually guide you to the right choice.

If you just want the best value without overthinking it:

We strongly recommend the ATO-ICDS-Z16.

Wide range: 0–50,000 ppm (expandable up to 150,000 ppm)

Works for home, commercial spaces (like meeting rooms or classrooms), and even industrial use (like fermentation rooms)

Fast response: T90 < 30 seconds

→ Quickly detects changes in CO₂ levels, great for real-time monitoring

Easy connection: Supports UART and PWM

→ Simple to integrate into your system

Why choose Z16:

Range: 0–50,000 ppm (up to 150,000 ppm)

Response: T90 < 30 seconds

Interface: UART / PWM

Use cases: Home, commercial, industrial fermentation

Price: $138.73

It’s a solid all-around choice that makes your decision much simpler.

30-second comparison table

Application scenario	Recommended range	Recommended accuracy	Recommended output	Recommended product	Price
Suitable for monitoring small plants, enclosed balconies, or indoor environments	0-5000ppm	±50ppm	UART/I2C	ATO-GS-CO2-Z19C	$104.56
Greenhouse applications	0-5000ppm	±50ppm	UART/I2C	ATO-ICDS-Z16	$138.73
Wide-coverage, all-in-one monitoring	0-50000ppm	±(50+5%FS) ppm	ModBus 485	ATO-GS-CO2-D622	$163.82
Beginners with a low budget and flexible output needs	0-5000ppm	±50ppm	UART/I2C	ATO-ICDS-Z14A	$103.33
Cost-effective choice for dynamic environments, limited budget, or secondary development projects	0–50,000 ppm, expandable up to 150,000 ppm	±50ppm	UART，PWM	ATO-ICDS-Z16	$138.73
Applications with extremely high requirements for protection, stability, or measurement range	0–100% Vol, or optional range of 0–50,000 ppm	1 ppm (in ppm range), 0.01% Vol (in Vol range)	Mini-USB	GD200-CO2	$969.23

Need help choosing the right sensor for your project?

Our engineering team offers free selection support. Just send us your application scenario, estimated maximum CO₂ level, and required output interface, and we’ll recommend the right model within 24 hours.