Least Count
The smallest scale division or magnitude that can be measured directly using a given instrument.
Governing formula
Least Count = Main Scale Division / Total Sub-divisions
SI unit
Various
In depth
Least count establishes instrument resolution and fundamental reading uncertainty. Finer least count reduces instrument reading error.
Examples in the real world
A standard meter ruler has a least count of 1 mm (0.1 cm), whereas a Vernier caliper typically has a least count of 0.1 mm (0.01 cm).