In metric, bolts and nuts are often measured in millimeters.

In metric, bolts and nuts are often measured in millimeters.

• A. Centimeters
• B. Inches
• C. Millimeters
• D. Meters

Answer: (C)

In the metric system, fastener sizes are specified in millimeters because bolt and thread dimensions are small and require precise, decimal-friendly measurements. The standard naming convention uses an M followed by the nominal diameter in millimeters (for example, M8, M12), and the thread pitch is also expressed in millimeters. Using millimeters keeps the measurements granular enough for accurate fitting and compatibility across parts. Centimeters and meters are too coarse for typical bolt sizes, which is why you don’t see fastener diameters expressed in those units in metric practice. Inches belong to the imperial system, which is not used for metric fasteners, so they wouldn’t be the measurement standard here. That’s why millimeters is the standard unit for metric bolts and nuts.

In the metric system, fastener sizes are specified in millimeters because bolt and thread dimensions are small and require precise, decimal-friendly measurements. The standard naming convention uses an M followed by the nominal diameter in millimeters (for example, M8, M12), and the thread pitch is also expressed in millimeters. Using millimeters keeps the measurements granular enough for accurate fitting and compatibility across parts.

Centimeters and meters are too coarse for typical bolt sizes, which is why you don’t see fastener diameters expressed in those units in metric practice. Inches belong to the imperial system, which is not used for metric fasteners, so they wouldn’t be the measurement standard here. That’s why millimeters is the standard unit for metric bolts and nuts.