NPT Thread Names Explained: MIP, FIP, MPT, MNPT, FNPT, FPT

NPT pipe threads have at least six common names: MIP, FIP, MPT, MNPT, FNPT, and FPT. They all refer to the same thread standard: National Pipe Taper per ANSI/ASME B1.20.1. The different names just indicate male or female gender. If you have been searching "MIP vs NPT" or "FIP vs NPT" wondering what the difference is, the answer is: there is no difference. They are the same thread.

What Each Name Means

NPT = National Pipe Taper. The formal name for the thread standard. MIP = Male Iron Pipe. An older plumbing industry term for a male NPT thread. FIP = Female Iron Pipe. The counterpart: a female NPT thread. MPT = Male Pipe Thread. Same as MIP, just a different abbreviation. MNPT = Male National Pipe Taper. The most explicit version: specifies male gender and the full standard name. FNPT = Female National Pipe Taper. Female version. FPT = Female Pipe Thread. Same as FIP and FNPT.

Why So Many Names?

The plumbing industry developed its own terminology (MIP/FIP) independent of the engineering standard name (NPT). Hardware stores typically label fittings as MIP or FIP. Manufacturer catalogs often use MPT/FPT. Engineering specs use MNPT/FNPT. Hydraulic catalogs usually just say NPT and specify the gender separately. All of these terms describe the same 60-degree tapered pipe thread.

MIP vs NPT

They are the same thing. MIP (Male Iron Pipe) is a male NPT fitting. When a hardware store label says "3/4 MIP" it means "3/4 inch male NPT thread." If your spec says NPT and the store only has MIP, buy it. It's the same thread.

FIP vs NPT

FIP (Female Iron Pipe) is a female NPT fitting. A "1/2 FIP" coupling has 1/2 inch female NPT threads on both ends. FIP is to female NPT as MIP is to male NPT.

MIP vs FIP

MIP is male (external threads, goes inside). FIP is female (internal threads, receives the male). A male NPT fitting threads into a female NPT fitting. The sizes must match: a 3/4 MIP threads into a 3/4 FIP.

What About NPTF?

NPTF (National Pipe Taper Fuel) is a different specification from NPT. While all the names above (MIP, FIP, MPT, etc.) are just gender labels for standard NPT, NPTF has tighter manufacturing tolerances designed to seal without thread tape or compound. See our NPT vs NPTF comparison for the full breakdown.

Quick Reference

MIP = MNPT = MPT = Male NPT. FIP = FNPT = FPT = Female NPT. If two fittings are both "NPT" in different name formats, they will thread together as long as the sizes match and one is male and one is female.