M24 screw or bolt dimensions and sizes are heavy-duty fasteners critical for structural steelwork, bridge girders, heavy industrial presses, and large-scale power generation equipment. This size has a 24.00mm nominal major diameter and is available in M24 x 3.0 for the coarse series and M24 x 2.0 for the fine series, where 3.0 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, Socket Head), manufacturer, or material grade — always verify with the official product datasheet before use.
M24 x 3.0 Screw & Bolt – DIN 13-1/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
23.577
23.952
Pitch Diameter
21.803
22.003
Minor Diameter
19.955
20.704
Thread Pitch
3.0
Major Diameter
23.557
23.952
Pitch Diameter
21.878
22.003
Minor Diameter
20.03
20.704
Thread Pitch
3.0
M24 x 2.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
23.682
23.962
Pitch Diameter
22.493
22.663
Minor Diameter
21.261
21.797
Thread Pitch
2.0
Major Diameter
23.682
23.962
Pitch Diameter
22.557
22.663
Minor Diameter
21.325
21.797
Thread Pitch
2.0
M24 x 1.5 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
23.732
23.968
Pitch Diameter
22.844
22.994
Minor Diameter
21.92
22.344
Thread Pitch
1.5
Major Diameter
23.732
23.968
Pitch Diameter
22.899
22.994
Minor Diameter
21.975
22.344
Thread Pitch
1.5
M24 x 1.0 Screw & Bolt – DIN 13-21/ISO 68-1
Dimension
Size (mm)
Min
Max
Major Diameter
23.794
23.974
Pitch Diameter
23.199
23.324
Minor Diameter
22.583
22.891
Thread Pitch
1.0
Major Diameter
23.794
23.974
Pitch Diameter
23.244
23.324
Minor Diameter
22.628
22.891
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 M24 screws or bolts?
For metric fasteners, the recommended tap drill size can be calculated using this formula: Major Diameter – Thread Pitch. For an M24 x 3.0 (Coarse), the recommended tap drill is 21.00mm. For an M24 x 2.0 (Fine), the recommended drill size is 22.00mm.
What clearance hole size is needed for an M24 screw or bolt?
For an M24 fastener, a 25.00mm drill bit is utilized for a Close Fit, a 26.00mm bit is used for a Normal Fit, and a 28.00mm bit is recommended for a Loose Fit. A Normal Fit is the industry standard to ensure the bolt shank passes through the assembly without binding while maintaining structural alignment.
What is the equivalent size for M24 in inch (imperial)?
For size M24, the nearest inch (imperial) match is 15/16".
This particular size has a maximum major diameter of 23.813 mm (0.9375 inch),
which means the measurement offset is only about 0.162 mm (0.00636 inch).
While these diameters are nearly identical, metric and imperial fasteners are not interchangeable. They utilize fundamentally different thread systems: Imperial fasteners are measured by Threads Per Inch (TPI), whereas metric fasteners use Thread Pitch. Mixing metric and imperial hardware is strongly discouraged, as it can lead to damaged components, reduced load-bearing capacity, and catastrophic mechanical failure.
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.
