Metric Nut
This metric nut size chart is based on globally applicable ISO standards and compiled manufacturer datasheets. Each size include one reference diagrams and a complete dimensions chart covering thread pitch, inner bearing diameter, outer bearing diameter, nut height, width across flats, width across corners, and with a built-in metric-to-inches converter for user from the United States.
How Metric Nut Sizes Work
Metric nuts are designated by the letter M followed by a number. The number represents the nominal major thread diameter of the mating bolt, in millimeters. For example, an M8 nut is designed to fit an M8 bolt with an 8 mm major diameter.
Thread Types: Coarse vs Fine
Metric nuts are manufactured with either coarse or fine internal threads. Coarse threads are the default ISO standard and are widely used in general applications. Fine threads provide improved load distribution and vibration resistance but are less common.
Nut Types and Forms
The nut type defines its external shape, height, and load-bearing characteristics. Common metric nut types include hex nuts, flange nuts, and lock nuts. These characteristics affect wrench size, clamping force, and suitability for specific applications.
ISO Metric Nut Standards
All metric nut sizes listed follow ISO fastener standards, which define internal thread geometry, bearing dimensions, nut height, and width across flats. ISO standards ensure compatibility between nuts and bolts from different manufacturers.