Bolt Thread Size Chart

This chart provides information on bolt thread sizes including the nominal size, thread pitch, major and minor diameter, and tap drill size for different sizes ranging from 1/4 inch to 1-1/2 inch.
Nominal Size (in) Thread Pitch (TPI) Major Diameter (in) Minor Diameter (in) Tap Drill Size (in)
1/4 20 0.2500 0.2170 7/32
5/16 18 0.3125 0.2750 F
3/8 16 0.3750 0.3340 5/16
7/16 14 0.4375 0.3910 U
1/2 13 0.5000 0.4500 27/64
5/8 11 0.6250 0.5670 17/32
3/4 10 0.7500 0.6875 11/16
7/8 9 0.8750 0.8065 49/64
1 8 1.0000 0.9270 7/8
1-1/8 7 1.1250 1.0450 31/32
1-1/4 7 1.2500 1.1700 1-1/8
1-1/2 6 1.5000 1.4100 1-5/16

The Bolt Thread Size Chart provides information about various bolt sizes, thread pitches, major and minor diameters, and corresponding tap drill sizes. This chart is useful for selecting the appropriate bolt for specific applications and ensuring proper compatibility with nuts and threaded holes. The nominal sizes range from 1/4 inch to 1-1/2 inches, and the thread pitches range from 20 TPI to 6 TPI. The chart also provides major and minor diameter measurements and tap drill size recommendations.


What is a bolt thread size chart?

A bolt thread size chart is a reference guide that provides information on the different thread sizes and dimensions of bolts, such as diameter, pitch, and length.

How do I determine the thread size of a bolt?

To determine the thread size of a bolt, you can measure the diameter using a caliper or a thread pitch gauge. The thread pitch can also be identified by counting the number of threads per inch or measuring the distance between threads.

What are the different thread size measurement standards?

The most common thread size measurement standards are the Unified Thread Standard (UNC/UNF), Metric Thread Standard (M), and the British Standard Whitworth (BSW). Each standard uses a different unit of measurement for diameter and pitch.

Are thread sizes the same for metric and imperial (inch-based) bolts?

No, metric and imperial bolt threads have different size standards. Metric bolts use the metric thread standard where the thread size is specified in millimeters, while imperial bolts use the Unified Thread Standard where the size is specified in inches.

What information can I find in a bolt thread size chart?

A bolt thread size chart typically provides information on bolt diameter, thread pitch, thread series type (fine or coarse), and commonly used applications for each thread size. It can also include specifications for external and internal thread measurements.

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We have not conducted any studies ourselves. Our article provides a summary of all the statistics and studies available at the time of writing. We are solely presenting a summary, not expressing our own opinion. We have collected all statistics within our internal database. In some cases, we use Artificial Intelligence for formulating the statistics. The articles are updated regularly.

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