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How to calibrate a temperature sensor?


This content originally appeared on DEV Community and was authored by Hedy

Calibrating a temperature sensor involves comparing its readings to a known accurate reference and adjusting for any error. Here’s how to do it step by step:

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1. Understand the Sensor Type
Common temperature sensors:

Calibration methods vary depending on the sensor type.

2. Gather Required Tools

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3. Perform Multi-Point Calibration
a. Prepare Calibration Points
Use 2–3 known temperatures:

  • Ice water (~0°C)
  • Room temperature (~20–25°C)
  • Warm water (~50–60°C) or boiling water (~100°C)

b. Measure Each Point

  • Place sensor and reference in the same environment
  • Let them stabilize for a few minutes
  • Record both sensor reading and actual temperature

4. Calculate Error or Offset
For digital sensors:
Use the offset or slope:

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float offset = reference_temp - sensor_reading;
float corrected = sensor_reading + offset;

For analog sensors or thermistors:

  • Create a calibration curve (e.g., linear or polynomial)
  • Use regression or map equations to adjust readings in code

5. Update Your Code
Example (Arduino):

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float rawTemp = readSensor();  // Your sensor reading function
float offset = -1.5;           // Calibrated offset
float correctedTemp = rawTemp + offset;

Or for scaling (linear correction):

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float scale = 1.02;
float offset = -1.1;
float correctedTemp = (rawTemp * scale) + offset;

6. Re-Test and Validate

  • Repeat the test with your corrected readings.
  • Confirm accuracy at different temperatures.

Tips

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This content originally appeared on DEV Community and was authored by Hedy