Cart

Connect with  

Gas Fittings

How to determine Pipe Thread Size

Pipe thread sizes do not refer to any physical dimensions. The outside diameter of each pipe fitting
must be measured and compared to the table for size identification. For example: a 1/4" NPT has an outside dimension of 0.54". This is especially important when looking for Regulator fittings.

NPT SIZE
THREAD DIAMETER
THREAD DIAMETER (O.D. of MPT or I.D.
of FPT)
1/8" NPT 0.405
1/4" NPT 0.54
3/8" NPT 0.675
1/2" NPT 0.84
3/4" NPT 1.05
1" NPT 1 1.315
1-1/4" NPT 1.66
1-1/2" NPT 1.9
2" NPT 2.375
2-1/2" NPT 2.875
3" NPT 3.5
4" NPT 4.5
Chudnow Mfg. Clearance