Tag Archives: humidity

DHT11 Humidity Temperature Sensor


Humidity is the amount of water vapor in the air. Water vapor is the gaseous state of water and is invisible. Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin.

 DHT11 Humidity Temperature Sensor

The DHT11 humidity and temperature sensor measures relative humidity (RH) and temperature. Relative humidity is the ratio of water vapor in air vs. the saturation point of water vapor in air. The saturation point of water vapor in air changes with temperature. Cold air can hold less water vapor before it is saturated, and hot air can hold more water vapor before it is saturated. The formula for relative humidity is as follows:

Relative Humidity = (density of water vapor / density of water vapor at saturation) x 100%

Basically, relative humidity is the amount of water in the air compared to the amount of water that air can hold before condensation occurs. It’s expressed as a percentage.  For example, at 100% RH condensation (or rain) occurs, and at 0% RH, the air is completely dry.

Components Used

  1. DHT11
  2. Arduino Uno
  3. Connecting Wires

DHT11 Sensor Pinout

DHT11 Pin out
DHT11 Pin out

DHT11 Arduino Circuit Diagram

DHT11 Arduino Circuit Diagram
DHT11 Arduino Circuit Diagram

Arduino Code for DHT11 Humidity Temperature Measurement

This code requires DHT11 Library Download From: https://github.com/adafruit/DHT-sensor-library

//Humidity and Temperature Measurement
#include <dht.h>

dht DHT;
#define DHT11_PIN 2

void setup(){

void loop()
  int chk = DHT.read11(DHT11_PIN);
  Serial.print("Temperature = ");
  Serial.print("Humidity = ");

DHT11 Humidity Temperature Measurement Result

Open serial monitor and observe the readings. Blowing air on sensor will change the humidity readings.

DHT11 Temperature Humidity Result
DHT11 Temperature Humidity Result

For more Weather related other parameters measurement see below links

  1. Barometric pressure measurement
  2. Rain Sensor interface with Arduino