4″ bolt or screw dimensions and sizes are specified for heavy industrial hydraulic turbines, high-pressure steam flanges, and primary structural anchoring. This size have a 4.000″ nominal major diameter and is available in 4″-4 coarse (UNC) thread pitch, representing 4 threads per inch (TPI). 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 extreme-scale 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.
4-4 UNC Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.9609
3.9966
Pitch Diameter
3.8172
3.8342
Minor Diameter
Not specified
3.6989
Threads Per Inch (TPI)
4
Major Diameter
3.9728
3.9966
Pitch Diameter
3.8229
3.8342
Minor Diameter
Not specified
3.6989
Threads Per Inch (TPI)
4
Major Diameter
3.9762
4
Pitch Diameter
3.8291
3.8376
Minor Diameter
Not specified
3.7023
Threads Per Inch (TPI)
4
4-6 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.9788
3.997
Pitch Diameter
3.8788
3.8887
Minor Diameter
Not specified
3.7985
Threads Per Inch (TPI)
6
Major Diameter
3.9818
4
Pitch Diameter
3.8843
3.8917
Minor Diameter
Not specified
3.8015
Threads Per Inch (TPI)
6
4-8 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.9823
3.9973
Pitch Diameter
3.907
3.9161
Minor Diameter
Not specified
3.8485
Threads Per Inch (TPI)
8
Major Diameter
3.985
4
Pitch Diameter
3.912
3.9188
Minor Diameter
Not specified
3.8512
Threads Per Inch (TPI)
8
4-12 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.9866
3.998
Pitch Diameter
3.9374
3.9439
Minor Diameter
Not specified
3.8988
Threads Per Inch (TPI)
12
Major Diameter
3.9886
4
Pitch Diameter
3.941
3.9459
Minor Diameter
Not specified
3.9008
Threads Per Inch (TPI)
12
4-16 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.9888
3.9982
Pitch Diameter
3.9517
3.9576
Minor Diameter
Not specified
3.9238
Threads Per Inch (TPI)
16
Major Diameter
3.9906
4
Pitch Diameter
3.955
3.9594
Minor Diameter
Not specified
3.9256
Threads Per Inch (TPI)
16
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.
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.
