What is the Least Count of Screw Gauge?

The Least Count of a Screw Gauge (also known as a micrometer screw gauge) is the smallest measurement that it can accurately measure.

Least Count of Screw Gauge is calculated using the following formula:

Least Count (LC) = Pitch of the Screw / Number of Divisions on the Circular Scale

Here’s what that means:

• Pitch of the Screw: This is the distance moved by the spindle per one complete rotation. It’s usually given in millimeters (mm).
• Number of Divisions on the Circular Scale: This is the total number of divisions marked on the circular scale of the screw gauge.

For instance, if the pitch of the screw is 0.5 mm (meaning the spindle moves 0.5 mm forward or backward with one complete turn), and the circular scale has 100 divisions, then the Least Count would be 0.5 mm / 100 = 0.005 mm.

The Least Count is crucial for understanding the precision of the screw gauge. A smaller Least Count means the instrument can measure smaller differences more accurately, making the screw gauge a vital tool in precision engineering, physics experiments, and other applications requiring fine measurements.