M45 bolt or screw dimensions and sizes are heavy-duty fasteners used in massive structural engineering projects, large-scale industrial turbines, heavy maritime propulsion, and primary industrial foundations. This size has a 45.00mm nominal major diameter and is available in M45 x 4.5 for the coarse series, where 4.5 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.
M45 x 4.5 Screw & Bolt – DIN 13-1/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
44.437
44.937
Pitch Diameter
41.778
42.014
Minor Diameter
39.006
40.066
Thread Pitch
4.5
Major Diameter
44.437
44.937
Pitch Diameter
41.864
42.014
Minor Diameter
39.092
40.066
Thread Pitch
4.5
M45 x 4.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
44.465
44.94
Pitch Diameter
42.118
42.342
Minor Diameter
39.654
40.61
Thread Pitch
4.0
Major Diameter
44.465
44.94
Pitch Diameter
42.202
42.342
Minor Diameter
39.738
40.61
Thread Pitch
4.0
M45 x 3.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
44.577
44.952
Pitch Diameter
42.803
43.003
Minor Diameter
40.955
41.704
Thread Pitch
3.0
Major Diameter
44.577
44.952
Pitch Diameter
42.878
43.003
Minor Diameter
41.03
41.704
Thread Pitch
3.0
M45 x 2.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
44.682
44.962
Pitch Diameter
43.493
43.663
Minor Diameter
42.261
42.797
Thread Pitch
2.0
Major Diameter
44.682
44.962
Pitch Diameter
43.557
43.663
Minor Diameter
42.325
42.797
Thread Pitch
2.0
M45 x 1.5 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
44.732
44.968
Pitch Diameter
43.844
43.994
Minor Diameter
42.92
43.344
Thread Pitch
1.5
Major Diameter
44.732
44.968
Pitch Diameter
43.899
43.994
Minor Diameter
42.975
43.344
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 M45 coarse screws or bolts?
For metric fasteners, the recommended tap drill size can be calculated using this formula: Major Diameter – Thread Pitch. For an M45 x 4.5 (Coarse), the recommended tap drill is 40.50mm.
What clearance hole size is needed for an M45 screw or bolt?
For an M45 fastener, a 46.00mm drill bit is utilized for a Close Fit, a 48.00mm bit is used for a Normal Fit, and a 52.00mm 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.
