Temperature and humidity sensor (DHT11)

01/05/2026

This is a simple project to build, perfect for beginners as well as for those with more experience. And the best part is that it's very accurate. It showed 22.2°C and 57%, just like a thermostat.

I did some research, and the recommended humidity level in a room should be between 40–60%. It's important not to go:

Below 30% → dry skin, irritation, static electricity risk
Above 70% → mold, dampness, and unpleasant smells

The temperature and humidity values will be displayed in the Serial Monitor.

Required components:

Arduino board (I used a Nano, but any Arduino-compatible microcontroller will work)
DHT11 or DHT22 sensor (3 pins: VCC, DATA, GND)
Jumper wires
Breadboard (optional, but recommended)

Connections:

Sensor VCC pin → Arduino 5V pin
Sensor GND pin → Arduino GND pin
Sensor DATA pin → Arduino pin 2

Code:

#include <DHT.h>

#define DHTPIN 2

#define DHTTYPE DHT11 // sau DHT22

DHT dht(DHTPIN, DHTTYPE);

void setup() {

Serial.begin(9600);

dht.begin();

}

void loop() {

delay(2000);

float h = dht.readHumidity();

float t = dht.readTemperature();

if (isnan(h) || isnan(t)) {

Serial.println("Eroare senzor");

return;

}

Serial.print("Temperatura: ");

Serial.print(t);

Serial.print(" °C | Umiditate: ");

Serial.print(h);

Serial.println(" %");

}