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Temperature from a Thermistor (Arduino)

Turn a 10k NTC thermistor and a resistor into a temperature sensor. Learn voltage dividers and the Beta equation.

Intermediate25 min

What you need

Wiring

Arduino Uno
Thermistor

Hover a pin or a wire to trace the connection.

Code

thermistor.ino
// Read temperature from a 10k NTC thermistor + 10k divider.
const int pin = A0;
const float BETA = 3950.0;   // use your thermistor's datasheet value

void setup() { Serial.begin(9600); }

void loop() {
  int raw = analogRead(pin);
  // Thermistor to 5V, 10k from A0 to GND:
  float r = 10000.0 * (1023.0 - raw) / raw;            // thermistor resistance
  float tempK = 1.0 / (1.0 / 298.15 + log(r / 10000.0) / BETA);
  Serial.print(tempK - 273.15);
  Serial.println(" C");
  delay(1000);
}

Steps

  1. Build the divider: thermistor from 5V to A0, and a 10kΩ resistor from A0 to GND.
  2. Put your thermistor's Beta value (from its datasheet) into the code.
  3. Upload and open the Serial Monitor to read the temperature.
  4. Pinch the thermistor — the temperature should climb.