Least count is the smallest value any instrument can read or measure. You may hear of vernier calliper of least count 0.02 mm, which means the minimum value vernier can measure is 0.02 mm.
You can’t measure a value less than 0.02 mm with this vernier calliper.
The same thing applied to all other instruments, a usual scale of least count of 1 mm, can measure a minimum length of 1 mm only.
Vernier Caliper is a widely used linear measurement instrument with the least count of 0.02 mm. It is used to measure linear dimensions like length, diameter, depth.
Let’s discuss common Mechanical measuring instruments with their least count (Considering least count of commonly used instruments, you may find changes in special cases)
|Vernier Caliper||0.02 mm|
|Digital Caliper||0.01 mm|
|Outsite Micrometre||0.01 mm|
|Vernier Micrometre||0.001 mm|
|Digital Micrometre||0.001 mm|
|Vernier Depth gauge||0.02 mm|
|Vernier Height Gauge||0.02 mm|
|Electronic Height Gauge||0.001 or 0.0001 mm|
|Glass scale||0.1 mm|
|Steel scale||1 mm|
|Bevel Protractor||5′ (5 second)|
|Depth Micrometer||0.01 mm|
|Digital Protractor||0.1 degree|
|Pressure gauge||1 bar|
|Digital Pressure gauge||0.01 bar|
|Pressure Calibrator||0.001 bar or 0.0001 bar|
|Laser Interferometer||0.1 nm (nanometre)|
|Dial gauge||0.01 mm|
|Measuring tape||1 mm|
There is a lot more, please comment below if you are looking for the least count of any instrument.