Screw Size Class; Thread Major Diameter Major Diameter Major Diameter Pitch Diameter Screw Size Class; Thread Basica Max Min Max 0‑80 2A 0.0600 0.0595 0.0563 0.0514 0‑80 3A 0.0600 0.0600 0.0568 0.0519

Internal and External Thread Dimensions - Dependable Acme Threaded Products Inc Acme General Purpose 2G Thread Series Limiting Dimensions & Tolerances The dimensions listed

The thread series is generally relative to the outside diameter of the screw. 20 threads per inch on a 1/4" diameter screw is considered coarse: 

Nominal Thread Size (inch), Major Diameter (mm), TPI (in-1). 1/16, 7.950, 27. 1/8, 10.287, 27. 1/4, 13.716, 18. 3/8, 17.145, 18. 1/2, 21.336, 14. 3/4 

The major diameter of the external thread has been calculated on the basis of a truncation of 0.10825 p, and the minor diameter of the internal thread has been calculated on the basis of a truncation of 0.21651 p, to provide no interference at crest and root when product is gaged with gages made in accordance with the Standard.

1⁄16 " NPT 27 0.3125 7.938 0.03704 0.941 0.02963 0.753 0.28118 1/8" NPT 27 0.405 10.287 0.03704 0.941 0.02963 0.753 0.0036 0.091 0.3736 9.489 1/4" NPT 18 0.54 13.716 0.05556 1.411 0.04444 1.129 0.0049 0.124 0.49163 12.487 3/8" NPT 18 0.675 17.145 0.05556 1.411 0.04444 1.129 0.0049 0.124 0.62701 15.926

UNF – Unified National Fine Thread and Male UNC/UNF threads are both parallel The UNC/UNF flank angle is 60° Unified threads comes in three different classes: for applications where a liberal tolerance is required to permit easy assembly even with slightly nicked threads most commonly used class for general applications

ANSI/ ASME EXTERNAL Screw Thread Size Chart. All units are in inches. Unified Screw Threads per. ANSI/ASME B1.1-1989 (R2001), R2001) Nomenclature, are used. Acceptability criteria are described in ANSI/ASME B1.3M-1992 (R2001).

SIZE TPI MAJOR (EXT) MINOR (INT) TAP DRILL 1/8" 28 9.728 8.566 8.70 1/4" 19 13.157 11.445 11.60 3/8" 19 16.662 14.950 15.00

British Standard Pipe BSP thread chart, BSP thread chart showing TPI and drill sizes.

95 rows · ANSI External Screw Threads Size & Tolerances Chart. Metric External (Fasteners)