What common tool is used to measure type size and leading in graphic design?

The tool that is most commonly used to measure type size and leading in graphic design is known as a pica ruler. A pica ruler is specifically designed for this purpose and includes units in points and picas, which are the traditional measurements used in typography.

A pica equals 12 points, and it is a standard measurement in the printing and design industries, allowing designers to accurately gauge type size and space between lines (leading). Using a pica ruler helps ensure consistency and precision in design work, which is crucial for maintaining the visual integrity of typography in any graphic design project.

While tools like a type gauge or E-scale might assist in different aspects of design or layout, they are not as universally recognized or widely used specifically for the measurement of type size or leading as the pica ruler. The measurement wheel is typically used for distance measurement in construction or landscape design, rather than typographic measurements. Thus, the pica ruler stands out as the most appropriate and common tool for this particular task.