M33 bolt or screw dimensions and sizes are heavy-duty fasteners typically reserved for heavy industrial infrastructure, large-scale maritime engineering, specialized mining equipment, and massive structural steel foundations. This size has a 33.00mm nominal major diameter and is available in M33 x 3.5 for the coarse series and M33 x 2.0 for the fine series, where 3.5 and 2.0 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, Studs), manufacturer, or material grade — always verify with the official product datasheet before use.
M33 x 3.5 Screw & Bolt – DIN 13-1/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
32.543
32.968
Pitch Diameter
30.483
30.695
Minor Diameter
28.327
29.179
Thread Pitch
3.5
Major Diameter
32.543
32.968
Pitch Diameter
30.563
30.695
Minor Diameter
28.407
29.179
Thread Pitch
3.5
M33 x 2.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
32.682
32.962
Pitch Diameter
31.493
31.663
Minor Diameter
30.261
30.797
Thread Pitch
2.0
Major Diameter
32.682
32.962
Pitch Diameter
31.557
31.663
Minor Diameter
30.325
30.797
Thread Pitch
2.0
M33 x 1.5 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
32.732
32.968
Pitch Diameter
31.844
31.994
Minor Diameter
30.92
31.344
Thread Pitch
1.5
Major Diameter
32.732
32.968
Pitch Diameter
31.899
31.994
Minor Diameter
30.975
31.344
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 M33 screws or bolts?
For metric fasteners, the recommended tap drill size can be calculated using this formula: Major Diameter – Thread Pitch. For an M33 x 3.5 (Coarse), the recommended tap drill is 29.50mm. For an M33 x 2.0 (Fine), the recommended drill size is 31.00mm.
What clearance hole size is needed for an M33 screw or bolt?
For an M33 fastener, a 34.00mm drill bit is utilized for a Close Fit, a 36.00mm bit is used for a Normal Fit, and a 38.00mm bit is recommended for a Loose Fit. A Normal Fit is the industry standard to ensure the large 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.
