9/16” Bolt & Screw Dimensions: Diameter & Head Size

9/16″ bolt dimensions and screw sizes are mostly used for industrial equipment, heavy-duty machinery, and large automotive assemblies. This size have a 0.563″ nominal major diameter and is available in 9/16″-12 coarse (UNC), 9/16″-18 fine (UNF), or 9/16″-24 extra-fine (UNEF) thread pitches, representing 12, 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
Hex head diagram
Cap head diagram
Low-cap head diagram
Button head diagram
Flat head diagram
Pan head diagram
9/16-12 UNC Screw & Bolt – ANSI/ASME B1.1
Dimension Size (in)
Min Max
Major Diameter 0.5437 0.5609
Pitch Diameter 0.499 0.5068
Minor Diameter Not specified 0.4617
Threads Per Inch (TPI) 12
Major Diameter 0.5495 0.5609
Pitch Diameter 0.5016 0.5068
Minor Diameter Not specified 0.4617
Threads Per Inch (TPI) 12
Major Diameter 0.5511 0.5625
Pitch Diameter 0.5045 0.5084
Minor Diameter Not specified 0.4633
Threads Per Inch (TPI) 12
9/16-16 UN Screw & Bolt – ANSI/ASME B1.1
Dimension Size (in)
Min Max
Major Diameter 0.5517 0.5611
Pitch Diameter 0.5158 0.5205
Minor Diameter Not specified 0.4867
Threads Per Inch (TPI) 16
Major Diameter 0.5531 0.5625
Pitch Diameter 0.5184 0.5219
Minor Diameter Not specified 0.4881
Threads Per Inch (TPI) 16
9/16-18 UNF Screw & Bolt – ANSI/ASME B1.1
Dimension Size (in)
Min Max
Major Diameter 0.548 0.5611
Pitch Diameter 0.5182 0.525
Minor Diameter Not specified 0.4949
Threads Per Inch (TPI) 18
Major Diameter 0.5524 0.5611
Pitch Diameter 0.5205 0.525
Minor Diameter Not specified 0.4949
Threads Per Inch (TPI) 18
Major Diameter 0.5538 0.5625
Pitch Diameter 0.523 0.5264
Minor Diameter Not specified 0.4963
Threads Per Inch (TPI) 18
9/16-20 UN Screw & Bolt – ANSI/ASME B1.1
Dimension Size (in)
Min Max
Major Diameter 0.5531 0.5612
Pitch Diameter 0.5244 0.5287
Minor Diameter Not specified 0.5017
Threads Per Inch (TPI) 20
Major Diameter 0.5544 0.5625
Pitch Diameter 0.5268 0.53
Minor Diameter Not specified 0.503
Threads Per Inch (TPI) 20
9/16-24 UNEF Screw & Bolt – ANSI/ASME B1.1
Dimension Size (in)
Min Max
Major Diameter 0.5541 0.5613
Pitch Diameter 0.5302 0.5342
Minor Diameter Not specified 0.5117
Threads Per Inch (TPI) 24
Major Diameter 0.5553 0.5625
Pitch Diameter 0.5324 0.5354
Minor Diameter Not specified 0.5129
Threads Per Inch (TPI) 24
9/16-2 UN Screw & Bolt – ANSI/ASME B1.1
Dimension Size (in)
Min Max
Major Diameter 0.5549 0.5614
Pitch Diameter 0.5345 0.5382
Minor Diameter Not specified 0.5189
Threads Per Inch (TPI) 2
Major Diameter 0.556 0.5625
Pitch Diameter 0.5365 0.5393
Minor Diameter Not specified 0.52
Threads Per Inch (TPI) 2
9/16-32 UN Screw & Bolt – ANSI/ASME B1.1
Dimension Size (in)
Min Max
Major Diameter 0.5554 0.5614
Pitch Diameter 0.5376 0.5411
Minor Diameter Not specified 0.5242
Threads Per Inch (TPI) 32
Major Diameter 0.5565 0.5625
Pitch Diameter 0.5396 0.5422
Minor Diameter Not specified 0.5253
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)
MinMax
Width Across Flats 0.798 0.812
Width Across Corners 0.91 0.938
Head Height 0.348 0.371
Hex Socket Cap Head – ANSI/ASME B18.3
Dimension Size (in)
MinMax
Head Diameter 0.827 0.843
Head Height 0.554 0.562
Hex Socket Size 7/16 (0.437 in)
Slotted Flat Head – ANSI/ASME B18.6.3
Dimension Size (in)
MinMax
Head Diameter 0.878 0.932
Head Height 0.26 Not specified
Slot Width 0.102 0.118
Slot Depth 0.077 0.12
Phillips Flat Head – ANSI/ASME B18.6.3
Dimension Size (in)
MinMax
Head Diameter 0.878 0.932
Head Height 0.26 Not specified
Drive Size 4
Phillips Pan Head – ANSI/ASME B18.6.3
Dimension Size (in)
MinMax
Head Diameter 1 1.041
Head Height 0.366 0.391
Drive Size 4
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Frequently Asked Questions

What is the tap drill size for 9/16″-12, 9/16″-18, and 9/16″-24 screws or bolts?

The appropriate tap drill depends on the target material and required thread engagement. For aluminum, brass, or plastic (75% thread), a 31/64″ (0.484″) drill bit is specified for 9/16″-12, and a 33/64″ (0.516″) drill bit is utilized for both 9/16″-18 and 9/16″-24. For steel, stainless, or iron (50% thread), a 33/64″ (0.516″) drill bit is recommended for 9/16″-12, and a 17/32″ (0.531″) drill bit is specified for both 9/16″-18 and 9/16″-24.

What clearance hole size is needed for a 9/16″ screw?

For a Close Fit, a 37/64″ (0.578″) drill bit is utilized. For a Normal/Free Fit (standard clearance), a 19/32″ (0.594″) drill bit is specified to allow the screw body to pass through the material without interference.

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.