Protractors and angle gages measure the angle between two surfaces of a part or assembly. Fixed angle gages, universal protractors, combination sets, protractor heads, sine bars, and "T" bevels are used for angular measurement. Protractors and angle gages fall under the category of measuring tools. Measuring tools are instruments and fixed gages that provide comparative and quantitative measurements of a product or component's dimensional, form and orientation attributes such as length, thickness, level, plumbness and squareness. Measuring or shop tools include rules, linear scales, protractors and angle gages, level and inclinometers, squares and fixed gages. Measuring tools are used in construction and building (contractors), drafting and drawing (designers), machine shops and tool rooms (machinists), field work (surveyors) and offices.

