M56 screw or bolt dimensions and sizes are extra-large fasteners critical for high-load industrial machinery, skyscraper foundations, massive bridge pylons, and heavy-duty turbine housings. This size has a 56.00mm nominal major diameter and is available in M56 x 5.5 for the coarse series, where 5.5 represents the thread pitch in millimeters. This reference chart follows respective DIN and ISO standards for each head style and DIN 13-1 (coarse) 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., Heavy Hex, Stud Bolts, Anchor Bolts), manufacturer, or material grade — always verify with the official product datasheet before use.
M56 x 5.5 Screw & Bolt – DIN 13-1/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
55.365
55.925
Pitch Diameter
52.088
52.353
Minor Diameter
48.7
49.971
Thread Pitch
5.5
Major Diameter
55.365
55.925
Pitch Diameter
52.183
52.353
Minor Diameter
48.795
49.971
Thread Pitch
5.5
M56 x 4.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
55.465
55.94
Pitch Diameter
53.106
53.342
Minor Diameter
50.642
51.61
Thread Pitch
4.0
Major Diameter
55.465
55.94
Pitch Diameter
53.192
53.342
Minor Diameter
50.728
51.61
Thread Pitch
4.0
M56 x 3.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
55.577
55.952
Pitch Diameter
53.791
54.003
Minor Diameter
51.943
52.704
Thread Pitch
3.0
Major Diameter
55.577
55.952
Pitch Diameter
53.871
54.003
Minor Diameter
52.023
52.704
Thread Pitch
3.0
M56 x 2.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
55.682
55.962
Pitch Diameter
54.483
54.663
Minor Diameter
53.251
53.797
Thread Pitch
2.0
Major Diameter
55.682
55.962
Pitch Diameter
54.551
54.663
Minor Diameter
53.319
53.797
Thread Pitch
2.0
M56 x 1.5 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
55.732
55.968
Pitch Diameter
54.834
54.994
Minor Diameter
53.91
54.344
Thread Pitch
1.5
Major Diameter
55.732
55.968
Pitch Diameter
54.894
54.994
Minor Diameter
53.97
54.344
Thread Pitch
1.5
M56 x 1.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
55.794
55.974
Pitch Diameter
55.184
55.324
Minor Diameter
54.568
54.891
Thread Pitch
1.0
Major Diameter
55.794
55.974
Pitch Diameter
55.234
55.324
Minor Diameter
54.618
54.891
Thread Pitch
1.0
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 M56 coarse screws or bolts?
For metric fasteners, the recommended tap drill size can be calculated using this formula: Major Diameter – Thread Pitch. For an M56 x 5.5 (Coarse), the recommended tap drill is 50.50mm.
What clearance hole size is needed for an M56 screw or bolt?
For an M56 fastener, a 58.00mm drill bit is utilized for a Close Fit, a 62.00mm bit is used for a Normal Fit, and a 66.00mm 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.
