M27 Nut Dimensions: Hex & Thin Series

Q: What size wrench or spanner do I need for an M27 nut?

An M27 hex nut typically requires a 41 mm wrench or socket. The standard width across flats (s) for an M27 nut is 41.00 mm. Due to the massive torque required to properly tension an M27 bolt, hydraulic torque wrenches or heavy-duty pneumatic impact tools are the industry standard for installation.

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 M27 fasteners, which are used in high-stress structural environments, using a thin nut as the primary fastener is highly unsafe as the threads are likely to strip or shear. Always use a Regular Series nut for primary load-bearing tasks.

M27 nut dimensions or sizes are critical for bridge girders, heavy-duty mining equipment, and large-scale industrial machinery. This size is specifically engineered to mate with fasteners having a 27.00 mm nominal diameter and is available in M27 x 3.0 for the coarse series and M27 x 2.0 for the fine series.

This charts is based on 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 heavy-load 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

M27 x 3.0 Hex Nut – DIN 13-1/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	27	27.698
Pitch Diameter	25.051	25.316
Minor Diameter	23.752	24.252
Thread Pitch	3.0

M27 x 2.0 Hex Nut – DIN 13-21/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	27	27.513
Pitch Diameter	25.701	25.925
Minor Diameter	24.835	25.21
Thread Pitch	2.0

M27 x 1.5 Hex Nut – DIN 13-21/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	27	27.417
Pitch Diameter	26.026	26.226
Minor Diameter	25.376	25.676
Thread Pitch	1.5

M27 x 1.0 Hex Nut – DIN 13-21/ISO 68-1
Dimension	Size (mm)
Dimension	Min	Max
Major Diameter	27	27.314
Pitch Diameter	26.35	26.52
Minor Diameter	25.917	26.153
Thread Pitch	1.0

M27 Hex Nut – DIN 934/ISO 4032 & ISO 8673
Diameter	27	29.1
Width Across Flats	40	41
Width Across Corners	45.2	Not specified
Height / Thickness	22.5	23.8

M27 Thin / Half Nut – DIN 439/ISO 4035 & ISO 8675
Diameter	27	29.2
Width Across Flats	40	41
Width Across Corners	45.2	Not specified
Height / Thickness	12.4	13.5

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Frequently Asked Questions

What size wrench or spanner do I need for an M27 nut?

An M27 hex nut typically requires a 41 mm wrench or socket. The standard width across flats (s) for an M27 nut is 41.00 mm. Due to the massive torque required to properly tension an M27 bolt, hydraulic torque wrenches or heavy-duty pneumatic impact tools are the industry standard for installation.

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 M27 fasteners, which are used in high-stress structural environments, using a thin nut as the primary fastener is highly unsafe as the threads are likely to strip or shear. Always use a Regular Series nut for primary load-bearing tasks.