Use externally calibrated [[Digital thermometer]] to calibrate digital display thermometer.
   ***For 2-8 degree**
   * keep the beaker full of water in refrigerator 24 hours before the calibration. 
   * At the time of calibration, keep all the thermometer along with calibrated thermometer inside the the beaker.
   * Keep beaker in refrigerator. After 15 minutes note the reading.
   ***For 0-30 degree**
   *keep all the thermometer along with calibrated thermometer inside the beaker full of water.
   *keep it in deep freezer for 4-5 hours or until water get freezed. note the readings. 
   ***For > 25 degree** 
   *keep all the thermometer along with calibrated thermometer inside the beaker full of water. 
   *keep it at room temperature for 1 hour. Note the readings.
Enter all the data in XL sheet.
Note the difference between observed value and nominal value(calibrated thermometer value), which should be less than **2 degree.**
Note down the difference on display thermometer.
Note the calibration data in LIS. and calibrate every 6 months.