Does a refractometer need regular calibration? How is it calibrated?

Yes. Handheld refractometers are intricate optical instruments, and they require regular calibration to ensure accurate measurements—especially after long-term use or when the device is exposed to significant temperature changes.

How to calibrate:

Calibration is typically done using a standard liquid, such as distilled water, which has a refractive index of 1.3330 at 20°C. Models that require special calibration liquid or other material (such as a standard calibration block) will come with these material. Follow the instructions in the user manual and adjust the calibration screw or knob until the reading matches the known reference value.