3-3/4” Bolt & Screw Dimensions: Diameter & Head Size
3-3/4″ bolt dimensions and screw sizes are specialized for massive industrial hydraulic presses, stadium structural supports, and heavy-vessel maritime engineering. This size have a 3.750″ nominal major diameter and is available in 3-3/4″-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.
3-3/4-4 UNC Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.7109
3.7466
Pitch Diameter
3.5674
3.5842
Minor Diameter
Not specified
3.4489
Threads Per Inch (TPI)
4
Major Diameter
3.7228
3.7466
Pitch Diameter
3.573
3.5842
Minor Diameter
Not specified
3.4489
Threads Per Inch (TPI)
4
Major Diameter
3.7262
3.75
Pitch Diameter
3.5792
3.5876
Minor Diameter
Not specified
3.4523
Threads Per Inch (TPI)
4
3-3/4-6 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.7289
3.7471
Pitch Diameter
3.629
3.6388
Minor Diameter
Not specified
3.5486
Threads Per Inch (TPI)
6
Major Diameter
3.7318
3.75
Pitch Diameter
3.6344
3.6417
Minor Diameter
Not specified
3.5515
Threads Per Inch (TPI)
6
3-3/4-8 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.7323
3.7473
Pitch Diameter
3.6571
3.6661
Minor Diameter
Not specified
3.5985
Threads Per Inch (TPI)
8
Major Diameter
3.735
3.75
Pitch Diameter
3.6621
3.6688
Minor Diameter
Not specified
3.6012
Threads Per Inch (TPI)
8
3-3/4-12 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.7367
3.7481
Pitch Diameter
3.6875
3.694
Minor Diameter
Not specified
3.6489
Threads Per Inch (TPI)
12
Major Diameter
3.7386
3.75
Pitch Diameter
3.691
3.6959
Minor Diameter
Not specified
3.6508
Threads Per Inch (TPI)
12
3-3/4-16 UN Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
3.7389
3.7483
Pitch Diameter
3.7019
3.7077
Minor Diameter
Not specified
3.6739
Threads Per Inch (TPI)
16
Major Diameter
3.7406
3.75
Pitch Diameter
3.705
3.7094
Minor Diameter
Not specified
3.6756
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.
