1-3/4” Bolt & Screw Dimensions: Diameter & Head Size

Q: What clearance hole size is needed for a 1-3/4″ bolt or screw?

For a Close Fit, a 1-49/64″ (1.766″) drill bit is utilized. For a Normal/Free Fit (standard clearance), a 1-25/32″ (1.781″) drill bit is specified to allow the bolt body to pass through the assembly 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.

1-3/4″ bolt dimensions and screw sizes are critical for primary structural foundations, bridge engineering, and massive industrial equipment mounting. This size have a 1.750″ nominal major diameter and is available in 1-3/4″-5 coarse (UNC) thread pitch, representing 5 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 large-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.

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

1-3/4-5 UNC Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	1.7165	1.7473
Pitch Diameter	1.604	1.6174
Minor Diameter	Not specified	1.5091
Threads Per Inch (TPI)	5
Major Diameter	1.7268	1.7473
Pitch Diameter	1.6085	1.6174
Minor Diameter	Not specified	1.5091
Threads Per Inch (TPI)	5
Major Diameter	1.7295	1.75
Pitch Diameter	1.6134	1.6201
Minor Diameter	Not specified	1.5118
Threads Per Inch (TPI)	5

1-3/4-6 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	1.7293	1.7475
Pitch Diameter	1.6309	1.6392
Minor Diameter	Not specified	1.549
Threads Per Inch (TPI)	6
Major Diameter	1.7318	1.75
Pitch Diameter	1.6354	1.6417
Minor Diameter	Not specified	1.5515
Threads Per Inch (TPI)	6

1-3/4-8 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	1.7327	1.7477
Pitch Diameter	1.659	1.6665
Minor Diameter	Not specified	1.5989
Threads Per Inch (TPI)	8
Major Diameter	1.735	1.75
Pitch Diameter	1.6631	1.6688
Minor Diameter	Not specified	1.6012
Threads Per Inch (TPI)	8

1-3/4-12 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	1.7368	1.7482
Pitch Diameter	1.6881	1.6941
Minor Diameter	Not specified	1.649
Threads Per Inch (TPI)	12
Major Diameter	1.7386	1.75
Pitch Diameter	1.6914	1.6959
Minor Diameter	Not specified	1.6508
Threads Per Inch (TPI)	12

1-3/4-16 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	1.739	1.7484
Pitch Diameter	1.7025	1.7078
Minor Diameter	Not specified	1.674
Threads Per Inch (TPI)	16
Major Diameter	1.7406	1.75
Pitch Diameter	1.7054	1.7094
Minor Diameter	Not specified	1.6756
Threads Per Inch (TPI)	16

1-3/4-20 UN Screw & Bolt – ANSI/ASME B1.1
Dimension	Size (in)
Dimension	Min	Max
Major Diameter	1.7404	1.7485
Pitch Diameter	1.7112	1.716
Minor Diameter	Not specified	1.689
Threads Per Inch (TPI)	20
Major Diameter	1.7419	1.75
Pitch Diameter	1.7139	1.7175
Minor Diameter	Not specified	1.6905
Threads Per Inch (TPI)	20

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	2.538	2.625
Width Across Corners	2.893	3.301
Head Height	1.054	1.196

Hex Socket Cap Head – ANSI/ASME B18.3
Dimension	Size (in)
Dimension	Min	Max
Head Diameter	2.597	2.625
Head Height	1.734	1.75
Hex Socket Size	1-1/4 (1.25 in)

Inch to Metric Converter

Enter inches to convert to mm

Previous & Next Size Chart
← 1-5/8
→ 2

← Choose Another Size

Frequently Asked Questions

What is the tap drill size for a 1-3/4″-5 screw or bolt?

Tap drill selection depends on the material hardness and the required thread engagement. For aluminum, brass, or plastic (75% thread), a 1-9/16″ (1.563″) drill bit is specified. For steel, stainless, or iron (50% thread), a 1-5/8″ (1.625″) drill bit is recommended to facilitate the threading process in harder materials.

What clearance hole size is needed for a 1-3/4″ bolt or screw?

For a Close Fit, a 1-49/64″ (1.766″) drill bit is utilized. For a Normal/Free Fit (standard clearance), a 1-25/32″ (1.781″) drill bit is specified to allow the bolt body to pass through the assembly 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.