Detects LPG, methane, butane, propane, hydrogen, alcohol and smoke
In stock
Gas
MQ-2 Smoke and Combustible Gas Sensor Module
MQ-2 gas sensor detecting LPG, methane, butane, hydrogen and smoke with analog and digital output.
₹90 + 18% GST
SKU: BOTBIT-SEN-12 · Best for: DIY smoke and fire early-warning detectors
Overview
About MQ-2 Smoke and Combustible Gas Sensor Module.
The MQ-2 is a metal-oxide semiconductor (MOS) gas sensor that detects combustible gases and smoke. Inside is a tin-dioxide (SnO2) sensing element whose resistance changes in the presence of target gases such as LPG, methane, butane, propane, hydrogen, alcohol and smoke. The module presents this as an analog voltage that rises with gas concentration, plus a digital output that trips at a threshold you set with the onboard potentiometer.
It is one of the most popular gas sensors for hobby smoke detectors, gas-leak alarms and safety projects in India because it is inexpensive and covers a broad range of common flammable gases in one part. Its dual output makes it flexible: read a graded value on an ADC, or wire the digital pin straight to a buzzer or relay for a standalone alarm.
The MQ-2 needs a brief warm-up before readings stabilise and gives a relative, not calibrated, reading, but for detecting the presence and rough level of smoke or gas leaks it is reliable and easy to use with Arduino, ESP32 and similar boards.
Key features
Why it stands out.
Dual output: analog (concentration-related) and digital (threshold trip)
Onboard LM393 comparator with potentiometer to set the digital alarm level
High sensitivity to combustible gases with fast response and recovery
Power and digital-output indicator LEDs for easy setup
Simple 4-pin interface (VCC, GND, AO, DO) that works with 5V logic
Specifications
Selection facts.
| Sensor | MQ-2 tin-dioxide (SnO2) MOS gas sensor |
|---|---|
| Target gases | LPG, methane, butane, propane, H2, alcohol, smoke |
| Detection range | Approx. 300 to 10,000 ppm (combustible gases) |
| Operating voltage | 5 V DC |
| Outputs | Analog (AO) + Digital (DO) |
| Comparator IC | LM393 |
| Heater / warm-up | Requires preheat; stable after warm-up (recommended 24-48h burn-in for accuracy) |
| Load / threshold | Adjustable digital threshold via onboard potentiometer |
Applications
Where it is used.
- DIY smoke and fire early-warning detectors
- LPG and combustible gas leak alarms for kitchens and workshops
- Portable gas-detection safety gadgets
- IoT air-safety monitoring with ESP32/ESP8266
- Educational projects on gas sensing and comparators
- Triggering exhaust fans or buzzers on gas detection
Buying guide
How to choose.
Choose the MQ-2 when you want a low-cost sensor that flags the presence of smoke or common flammable gases like LPG and methane. It is ideal for hobby gas-leak and smoke alarms. It is not a calibrated laboratory instrument and cannot distinguish exactly which gas is present, so do not rely on it alone for life-safety in critical settings; use a certified detector there.
Pair it with a microcontroller that has an ADC (Arduino, ESP32, ESP8266) to read the graded analog level, or use the digital output straight into a buzzer/relay for a codeless alarm. Set the digital threshold with the onboard potentiometer while watching the output LED. For any meaningful analog readings, give the sensor a warm-up period, and a longer initial burn-in improves stability.
If you specifically need air-quality/CO2-type monitoring rather than combustible-gas detection, the MQ-135 is the better companion or alternative.
FAQ
Common questions.
How do I wire the MQ-2 to an Arduino?
Connect VCC to 5V, GND to GND, AO to an analog pin (like A0) for the concentration reading, and DO to a digital pin if you want the threshold trip. The sensor draws noticeable current for its heater, so power it from a stable 5V.
Does it need a library?
Not necessarily. You can read AO with analogRead() and DO with digitalRead() directly. Libraries like MQUnifiedsensor exist to help convert readings to estimated ppm, but they require calibration.
Why is my reading high at first?
MQ-2 sensors need to warm up. Readings drift for the first minutes after power-on, and a longer initial burn-in of a day or two gives the most stable results. Always let it stabilise before trusting values.
Can it tell me the exact gas and concentration?
No. It responds to several combustible gases together and gives a relative reading. Without careful calibration against a known gas it cannot report a precise, gas-specific ppm value.
Is it a replacement for a certified smoke alarm?
No. It is great for learning and DIY projects, but for life-safety fire/gas protection you should use a certified, calibrated detector.
What is in the box?
You receive one MQ-2 gas sensor module with the sensor element, LM393 comparator, threshold potentiometer, indicator LEDs and a 4-pin header.
More in Sensors & Modules
Related hardware.
Gas
MQ-135 Air Quality Gas Sensor Module
Air quality sensor detecting CO2, ammonia, NOx, benzene and smoke, popular for air-quality and IoT monitors.
₹110 + 18% GST
Environment
DHT11 Digital Temperature and Humidity Sensor Module
Low-cost single-wire digital temperature (0-50C) and humidity (20-90% RH) sensor, the default beginner Arduino sensor.
₹60 + 18% GST
Environment
DHT22 / AM2302 Temperature and Humidity Sensor Module
Higher-accuracy digital temperature (-40 to 80C) and humidity (0-100% RH) sensor, upgrade over DHT11.
₹199 + 18% GST
Environment
BME280 Temperature Humidity Barometric Pressure Sensor Module (I2C/SPI)
Bosch 3-in-1 sensor measuring temperature, humidity and barometric pressure over I2C/SPI, popular for weather and altitude projects.
₹190 + 18% GST
You may also need
Pairs well with.
Arduino Boards
Arduino Uno R3
The classic ATmega328P 8-bit microcontroller board, a popular beginner prototyping platform with 14 digital and 6 analog I/O pins.
₹799 + 18% GST
Breadboards Jumpers
MB102 830 Points Solderless Breadboard
Full-size 830 tie-point solderless prototyping breadboard with power rails, accepts 20-29 AWG wire.
₹90 + 18% GST