M1 Nut Dimensions: Thread & Diameter

Q: What size wrench or spanner do I need for an M1 nut?

An M1 hex nut requires a 2.5 mm wrench or socket. This is because the standard width across flats (s) for an M1 nut (DIN 934) is 2.50 mm. Due to the miniature size, precision micro-tools or ESD-safe tweezers are often used for installation.

Q: In what applications are M1 nuts most common?

M1 nuts are primarily used in precision engineering, such as securing components in smartphones, high-end mechanical watches, and miniature sensors where space and weight savings are the highest priority.

M1 nut dimensions or sizes are critical for micro-electronics, watchmaking (horology), and medical device instrumentation. This size is specifically engineered to mate with fasteners having a 1.00 mm nominal diameter and is available in M1 x 0.25 for the coarse series, and M1 x 0.2 for the fine series where the 0.25 and 0.2 represents the thread pitch in millimeters.

This charts is based on (DIN 934 / ISO 4032) standard for a regular series hex nut. The thread dimensions comply with DIN 13-1 (coarse series), DIN 13-21 (fine series) and ISO 68-1 standards to ensure a precise fit and reliable engagement across ultra-fine metric fastening systems.

Disclaimer: Actual dimensions, including the width across flats (spanner or wrench size), nut height, and thread tolerance may vary depending on the specific manufacturing class and material — always verify with the official product datasheet before use or buying.

Nut internal thread diagram depicting major diameter, minor diameter, and pitch diameter

Nut body diagram depicting width across flats, width across corners, diameter, and thickness or height

M1 x 0.25 Hex Nut – DIN 13-1/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	1	1.107
Pitch Diameter	0.838	0.909
Minor Diameter	0.729	0.809
Thread Pitch	0.25

M1 x 0.2 Hex Nut – DIN 13-21/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	1	1.092
Pitch Diameter	0.87	0.933
Minor Diameter	0.783	0.858
Thread Pitch	0.2

M1 Hex Nut – DIN 934/ISO 4032 & ISO 8673
Diameter	1	1.15
Width Across Flats	2.4	2.5
Width Across Corners	2.71	Not specified
Height / Thickness	0.55	0.8

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Frequently Asked Questions

What size wrench or spanner do I need for an M1 nut?

An M1 hex nut requires a 2.5 mm wrench or socket. This is because the standard width across flats (s) for an M1 nut (DIN 934) is 2.50 mm. Due to the miniature size, precision micro-tools or ESD-safe tweezers are often used for installation.

In what applications are M1 nuts most common?

M1 nuts are primarily used in precision engineering, such as securing components in smartphones, high-end mechanical watches, and miniature sensors where space and weight savings are the highest priority.