Which tool is most commonly used for precision measurement in engineering?

The tool most commonly used for precision measurement in engineering is the caliper. Calipers are designed to measure internal and external dimensions as well as depths with a high degree of accuracy. They can measure small increments, often down to fractions of a millimeter or a thousandth of an inch, making them invaluable for tasks that require precise measurements, such as machining and fabrication.

Measuring tapes, while useful for longer distances and basic measurements, generally do not provide the fine precision that calipers do. Levels serve a different purpose, which is to determine whether a surface is horizontal or vertical, and are not used for measuring dimensions. Protractors are specifically used for measuring angles and do not apply to dimensional measurements in the same way as calipers. Therefore, the caliper stands out as the most appropriate tool for precision measurements in engineering contexts.