American National Pipe Taper (NPT), Like British Standard Pipe (BSP), is designated by trade size, rather than actual diameter, as shown in the NPT/NPS Table.

NPT threads are also sometimes referred to as

• MIP (Male Iron Pipe)
• FIP (Female Iron Pipe)
• IPT (Iron Pipe Thread)
• FPT (Female Pipe Thread)
• MPT (Male Pipe Thread)

Note that these are casual references.

NPT threads have a 60° included angle and have flat peaks and valleys (this is a Sellers thread form).