National Pipe Thread Chart

NPT or National Pipe Thread is an American thread type commonly used in a variety of hydraulic and industrial applications. The most recognizable characteristic of NPT are tapered threads, and due to the metal-to-metal sealing method of NPT thread sealant is required in order to achieve a leak free connection.

 

Inch	Dash Size	Nominal Thread Size	Male	Female
Fraction	Numeric	Fraction-Threads Per Inch	O.D.	I.D.
1/8	2	1/8-27	.41	.38
1/4	4	1/4-18	.54	.49
3/8	6	3/8-18	.68	.63
1/2	8	1/2-14	.84	.77
3/4	12	3/4-14	1.05	.98
1	16	1-11 1/2	1.32	1.24
1-1/4	20	1 1/4 - 11 1/2	1.66	1.58
1-1/2	24	1 1/2 - 11 1/2	1.90	1.82
2	32	2-11 1/2	2.38	2.30