5/8” Bolt & Screw Dimensions: Diameter & Head Size

Q: What clearance hole size is needed for a 5/8″ screw or bolt?

For a Close Fit, a 41/64″ (0.641″) drill bit is utilized. For a Normal/Free Fit (standard clearance), a 21/32″ (0.656″) drill bit is specified to allow the screw or the bolt body to pass through the material without binding.

Q: 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 holes 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.

5/8″ bolt dimensions and screw sizes are essential for heavy-duty structural applications, industrial base mounts, and high-torque mechanical assemblies. This size have a 0.625″ nominal major diameter and is available in 5/8″-11 coarse (UNC), 5/8″-18 fine (UNF), or 5/8″-24 extra-fine (UNEF) thread pitches, representing 11, 18, and 24 threads per inch (TPI) respectively. This reference chart follows ANSI/ASME B18.6.3 and B18.3 standards for the head size and ANSI/ASME B1.1 standards for the thread dimensions to ensure compatibility across imperial fastening applications.

Disclaimer: Dimensions and tolerances may vary slightly depending on head style, manufacturer, or material — always verify with the official product datasheet before use.

Thread diagram fot bolt and screw depicting the major diameter, minor diameter, pitch diameter, and threads per inch

5/8-11 UNC Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.6051	0.6233
Pitch Diameter	0.556	0.5643
Minor Diameter	Not specified	0.515
Threads Per Inch (TPI)	11
Major Diameter	0.6112	0.6233
Pitch Diameter	0.5588	0.5643
Minor Diameter	Not specified	0.515
Threads Per Inch (TPI)	11
Major Diameter	0.6129	0.625
Pitch Diameter	0.5619	0.566
Minor Diameter	Not specified	0.5167
Threads Per Inch (TPI)	11

5/8-12 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.612	0.6234
Pitch Diameter	0.5639	0.5693
Minor Diameter	Not specified	0.5242
Threads Per Inch (TPI)	12
Major Diameter	0.6136	0.625
Pitch Diameter	0.5668	0.5709
Minor Diameter	Not specified	0.5258
Threads Per Inch (TPI)	12

5/8-16 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.6142	0.6236
Pitch Diameter	0.5782	0.583
Minor Diameter	Not specified	0.5492
Threads Per Inch (TPI)	16
Major Diameter	0.6156	0.625
Pitch Diameter	0.5808	0.5844
Minor Diameter	Not specified	0.5506
Threads Per Inch (TPI)	16

5/8-18 UNF Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.6105	0.6236
Pitch Diameter	0.5805	0.5875
Minor Diameter	Not specified	0.5574
Threads Per Inch (TPI)	18
Major Diameter	0.6149	0.6236
Pitch Diameter	0.5828	0.5875
Minor Diameter	Not specified	0.5574
Threads Per Inch (TPI)	18
Major Diameter	0.6163	0.625
Pitch Diameter	0.5854	0.5889
Minor Diameter	Not specified	0.5588
Threads Per Inch (TPI)	18

5/8-20 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.6156	0.6237
Pitch Diameter	0.5869	0.5912
Minor Diameter	Not specified	0.5642
Threads Per Inch (TPI)	20
Major Diameter	0.6169	0.625
Pitch Diameter	0.5893	0.5925
Minor Diameter	Not specified	0.5655
Threads Per Inch (TPI)	20

5/8-24 UNEF Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.6166	0.6238
Pitch Diameter	0.5927	0.5967
Minor Diameter	Not specified	0.5742
Threads Per Inch (TPI)	24
Major Diameter	0.6178	0.625
Pitch Diameter	0.5949	0.5979
Minor Diameter	Not specified	0.5754
Threads Per Inch (TPI)	24

5/8-28 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.6174	0.6239
Pitch Diameter	0.5969	0.6007
Minor Diameter	Not specified	0.5814
Threads Per Inch (TPI)	28
Major Diameter	0.6185	0.625
Pitch Diameter	0.599	0.6018
Minor Diameter	Not specified	0.5825
Threads Per Inch (TPI)	28

5/8-32 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	0.6179	0.6239
Pitch Diameter	0.6	0.6036
Minor Diameter	Not specified	0.5867
Threads Per Inch (TPI)	32
Major Diameter	0.619	0.625
Pitch Diameter	0.602	0.6047
Minor Diameter	Not specified	0.5878
Threads Per Inch (TPI)	32

Major Diameter – The largest diameter of the external thread, measured crest to crest. This defines the nominal size of the screw or bolt.
Pitch Diameter – The diameter of an imaginary cylinder where the thread thickness equals the space between threads. This dimension primarily controls thread fit and tolerance class of 2A and 3A.
Minor Diameter – The smallest diameter of the external thread, measured root to root. This affects thread strength and clearance.
Threads Per Inch (TPI) – The number of complete threads within one inch of thread length. Higher TPI values indicate a finer thread pitch.

Hex Head – ANSI/ASME B18.2.1
Dimension	Size (in)
Dimension	Min	Max
Width Across Flats	0.906	0.938
Width Across Corners	1.033	1.083
Head Height	0.378	0.444

Hex Socket Cap Head – ANSI/ASME B18.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	0.914	0.938
Head Height	0.616	0.625
Hex Socket Size	1/2 (0.5 in)

Hex Socket Low Cap Head – ANSI/ASME B18.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	0.867	0.875
Head Height	0.306	0.316
Hex Socket Size	5/16 (0.312 in)

Hex Socket Button Head – ANSI/ASME B18.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	0.97	1
Head Height	0.311	0.331
Hex Socket Size	3/8 (0.375 in)

Hex Socket Flat Head – ANSI/ASME B18.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	1.112	1.188
Head Height	0.324	Not specified
Hex Socket Size	3/8 (0.375 in)

Slotted Flat Head – ANSI/ASME B18.6.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	0.99	1.05
Head Height	0.298	Not specified
Slot Width	0.116	0.133
Slot Depth	0.088	0.137

Phillips Flat Head – ANSI/ASME B18.6.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	0.99	1.05
Head Height	0.298	Not specified
Drive Size	5

Phillips Pan Head – ANSI/ASME B18.6.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	1.125	1.172
Head Height	0.406	0.434
Drive Size	5

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Frequently Asked Questions

What is the tap drill size for 5/8″-11, 5/8″-18, and 5/8″-24 screws or bolts?

The appropriate tap drill depends on the material and required thread engagement. For aluminum, brass, or plastic (75% thread), a 17/32″ (0.531″) drill bit is recommended for 5/8″-11, while a 37/64″ (0.578″) drill bit is specified for both 5/8″-18 and 5/8″-24. For steel, stainless, or iron (50% thread), a 9/16″ (0.563″) drill bit is recommended for 5/8″-11, and a 19/32″ (0.594″) drill bit is utilized for both 5/8″-18 and 5/8″-24.

What clearance hole size is needed for a 5/8″ screw or bolt?

For a Close Fit, a 41/64″ (0.641″) drill bit is utilized. For a Normal/Free Fit (standard clearance), a 21/32″ (0.656″) drill bit is specified to allow the screw or the bolt body to pass through the material without binding.

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 holes 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.