M39 bolt or screw dimensions and sizes are heavy-duty industrial fasteners utilized in large-scale infrastructure, heavy engine blocks, industrial smelting equipment, and massive structural baseplates. This size has a 39.00mm nominal major diameter and is available in M39 x 4.0 for the coarse series, where 4.0 represent the thread pitch in millimeters. This reference chart follows respective DIN and ISO standards for each head style and DIN 13-1 (coarse), DIN 13-21 (fine), and ISO 68-1 standards for thread dimensions to ensure global compatibility.
Disclaimer: Actual dimensions and tolerances may vary slightly depending on head style (e.g., Hex Head, Heavy Hex, Stud Bolts), manufacturer, or material grade — always verify with the official product datasheet before use.
M39 x 4.0 Screw & Bolt – DIN 13-1/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
38.465
38.94
Pitch Diameter
36.118
36.342
Minor Diameter
33.654
34.61
Thread Pitch
4.0
Major Diameter
38.465
38.94
Pitch Diameter
36.202
36.342
Minor Diameter
33.738
34.61
Thread Pitch
4.0
M39 x 3.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
38.577
38.952
Pitch Diameter
36.803
37.003
Minor Diameter
34.955
35.704
Thread Pitch
3.0
Major Diameter
38.577
38.952
Pitch Diameter
36.878
37.003
Minor Diameter
35.03
35.704
Thread Pitch
3.0
M39 x 2.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
38.682
38.962
Pitch Diameter
37.493
37.663
Minor Diameter
36.261
36.797
Thread Pitch
2.0
Major Diameter
38.682
38.962
Pitch Diameter
37.557
37.663
Minor Diameter
36.325
36.797
Thread Pitch
2.0
M39 x 1.5 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
38.732
38.968
Pitch Diameter
37.844
37.994
Minor Diameter
36.92
37.344
Thread Pitch
1.5
Major Diameter
38.732
38.968
Pitch Diameter
37.899
37.994
Minor Diameter
36.975
37.344
Thread Pitch
1.5
Major Diameter –
The largest diameter of the external thread, measured crest to crest.
This defines the nominal size (e.g., M12 which is 12 mm of nominal major diameter).
Pitch Diameter –
The diameter of an imaginary cylinder where the thread thickness equals
the space between threads. This is the critical dimension for thread fit
(Tolerance classes 2A/3A for Imperial; 6g/4g6g for Metric).
Minor Diameter –
The smallest diameter of the external thread, measured root to root.
This represents the core strength of the fastener and is the theoretical
maximum diameter of the tap drill.
Thread Pitch –
The distance from a point on one thread to the corresponding point on the next.
What is the tap drill size for M39 screws or bolts?
For metric fasteners, the recommended tap drill size can be calculated using this formula: Major Diameter – Thread Pitch. For an M39 x 4.0 (Coarse), the recommended tap drill is 35.00mm.
What clearance hole size is needed for an M39 screw or bolt?
For an M39 fastener, a 40.00mm drill bit is utilized for a Close Fit, a 42.00mm bit is used for a Normal Fit, and a 45.00mm bit is recommended for a Loose Fit. A Normal Fit is the industry standard to ensure the massive bolt shank passes through the assembly without binding while maintaining structural alignment.
What is the difference between a bolt and a screw?
The difference is based on the intent of the fastener’s use; If the primary intent is for the fastener to pass through an unthreaded hole and be assembled with a nut, it is a Bolt. In this application, you usually hold the head and turn the nut to apply tension. But if the primary intent is for the fastener to be installed into a threaded (tapped) hole, it is a Screw. In this application, the connection is tightened by turning the head of the fastener itself.
