Common metric bolt dimensions include bolts with a 4-millimeter diameter and 7-millimeter head/wrench size, according to American National Standards Institute/International Organization for Standardization measurements. Other common bolt dimensions are a 12-millimeter diameter and 18-millimeter head/wrench size, up to a 20-millimeter diameter and 30-millimeter head/wrench size under ANSI/IOS measurements.
Common metric flange bolt diameters range start at 5 millimeters. Six-millimeter bolts have a head/wrench size of 10 millimeters under the Japanese Industrial Standard B1189, Type 2, 2005. Ten-millimeter bolts have a 14-millimeter head/wrench size under the JIS. The largest flange bolt size is 20 millimeters, but it does not have a corresponding JIS measurement. Its head/wrench size is 27 measured by Deutsches Institut für Normung, DIN 6921, 1983.