M16 Nut Dimensions: Hex & Thin Series

Q: What size wrench or spanner do I need for an M16 nut?

An M16 hex nut requires a 24 mm wrench or socket. While some specialized heavy-duty variants may vary, 24.00 mm is the standard width across flats (s) for both DIN 934 and ISO 4032 standards.

Q: What is a jam nut?

A jam nut is a low-profile hex nut, typically from the Thin Series (DIN 439), that is used to lock a standard nut in place. By tightening a standard nut against a jam nut, you create internal tension between the threads of both nuts and the bolt. This “jams” the assembly together, providing a mechanical lock that prevents loosening caused by vibration or rotation.

Q: Can a Thin Series nut handle the same torque as a Regular nut?

No. Because the Thin Series has fewer threads in contact with the bolt, it has a lower proof load. For an M16 fastener, which often carries significant loads, using a thin nut as the primary fastener is dangerous as the threads are likely to shear or strip under high tension. Always use a Regular Series nut for structural integrity.

Q: Why is M16 a standard in structural engineering?

M16 is often the “baseline” size for steel-to-steel connections in building frames and industrial platforms. It provides a massive jump in clamping force and tensile strength over M12 or M14, making it suitable for supporting significant dead loads and resisting shear forces in construction.

M16 nut dimensions or sizes are critical for structural steel beams, heavy industrial machinery, and bridge construction. This size is specifically engineered to mate with fasteners having a 16.00 mm nominal diameter and is available in M16 x 2.0 for the coarse series and M16 x 1.5 for the fine series.

This charts covers both the Regular Series (DIN 934 / ISO 4032) for standard load-bearing applications and the Thin or Half Series (DIN 439 / ISO 4035), which is ideal for jam nut or lock nut configurations or applications with limited vertical clearance. The thread dimensions comply with DIN 13-1 (coarse), DIN 13-21 (fine series), and ISO 68-1 standards to ensure a precise fit and reliable engagement across high-capacity 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

M16 x 2.0 Hex Nut – DIN 13-1/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	16	16.501
Pitch Diameter	14.701	14.913
Minor Diameter	13.835	14.21
Thread Pitch	2.0

M16 x 1.5 Hex Nut – DIN 13-21/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	16	16.406
Pitch Diameter	15.026	15.216
Minor Diameter	14.376	14.676
Thread Pitch	1.5

M16 x 1.0 Hex Nut – DIN 13-21/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	16	16.304
Pitch Diameter	15.35	15.51
Minor Diameter	14.917	15.153
Thread Pitch	1.0

M16 Hex Nut – DIN 934/ISO 4032 & ISO 8673
Diameter	16	17.3
Width Across Flats	23.67	24
Width Across Corners	26.75	Not specified
Height / Thickness	14.1	14.8

M16 Thin / Half Nut – DIN 439/ISO 4035 & ISO 8675
Diameter	16	17.3
Width Across Flats	23.67	24
Width Across Corners	26.75	Not specified
Height / Thickness	7.42	8

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Frequently Asked Questions

What size wrench or spanner do I need for an M16 nut?

An M16 hex nut requires a 24 mm wrench or socket. While some specialized heavy-duty variants may vary, 24.00 mm is the standard width across flats (s) for both DIN 934 and ISO 4032 standards.

What is a jam nut?

A jam nut is a low-profile hex nut, typically from the Thin Series (DIN 439), that is used to lock a standard nut in place. By tightening a standard nut against a jam nut, you create internal tension between the threads of both nuts and the bolt. This “jams” the assembly together, providing a mechanical lock that prevents loosening caused by vibration or rotation.

Can a Thin Series nut handle the same torque as a Regular nut?

No. Because the Thin Series has fewer threads in contact with the bolt, it has a lower proof load. For an M16 fastener, which often carries significant loads, using a thin nut as the primary fastener is dangerous as the threads are likely to shear or strip under high tension. Always use a Regular Series nut for structural integrity.

Why is M16 a standard in structural engineering?

M16 is often the “baseline” size for steel-to-steel connections in building frames and industrial platforms. It provides a massive jump in clamping force and tensile strength over M12 or M14, making it suitable for supporting significant dead loads and resisting shear forces in construction.