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
• Environment

Choose NDIR (non-dispersive infrared) CO2 sensors for reliability. For most indoor uses, a 0–5000 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 the last appendix.

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

Will it work for my space? 

To find out, you need to know how different CO2 levels affect people and plants. Here’s a quick guide:

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

Now that you know what the numbers mean, here’s how to pick the right range for what you need. Choose based on your use:

 Once you know the range you need, here’s a product that fits well for wider coverage.

If you want wide coverage and all-in-one monitoring, the infrared CO2 transmitter ATO-GS-CO2-D622 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 (±50 ppm vs ±30ppm)

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

• Example: True CO2 is 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

But what does that accuracy mean for your plants? Let's look at two real-life examples.

If you just want something simple:

If you're thinking, "I just want a CO2 sensor to keep my plants from dying", then the infrared CO2 sensor module 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 it.

• 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, and 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 with less accuracy 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：

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 NDIR CO2 sensor module 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 transmitter 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 it is needed in the greenhouse, then choose a high-humidity-resistant model.
• If it is needed in the factory, then dust-proof and vibration-resistant
• Outdoor, then waterproof and 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:

• Check the environment first
  Is it high humidity, corrosive, or explosive? These conditions can affect CO2 monitor performance and safety.
• Choose certified protection
  Pick models with protective or explosion-proof certifications. This ensures safe use in dangerous areas.
• Estimate the highest CO2 level
  Know the maximum gas concentration in your environment before choosing a sensor.
• Match the measurement range
  Make sure the sensor’s range fully covers your expected gas levels.
• Compare prices last
  After safety and performance are confirmed, 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, the portable CO2 infrared gas detector GD200-CO2.

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 environment — that will usually guide you to the right choice.

If you just want the best value without overthinking it:

We strongly recommend the NDIR CO2 gas sensor.

• Wide range: 0–50,000 ppm (expandable up to 150,000 ppm), which works for home, commercial spaces (like meeting rooms or classrooms), and even industrial use (like fermentation rooms)
• Fast response: T90 < 30 seconds, which quickly detects changes in CO2 levels, great for real-time monitoring
• Easy connection: Supports UART and PWM, which is simple to integrate into your system

Why choose the NDIR CO2 gas sensor:

• Impressive Detection Range: 0–50,000 ppm (extendable to 150,000 ppm) means it is ideal for everything from indoor air quality monitoring to intense industrial fermentation processes.
• Rapid Response: Achieve critical data insights with a response time of T90 < 30 seconds.
• Seamless Integration: Dual interface support via UART and PWM ensures compatibility with most controllers and IoT gateways.
• Versatile Application: Whether it’s commercial HVAC systems or high-stakes industrial labs, the Z16 delivers consistent, low-drift performance.
• Price: $138.73 — Professional-grade sensing at a competitive value.

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

30-second comparison table

Search the model names in the table to view product details.

If none of these CO2 sensors work for you, just click here: CO2 Sensor Product Catalog — and find the one you need yourself.

Need help choosing the right sensor for your project?

Our ATO.com 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.