Pipe Size & Fitting Chart

Pipe and pipe fitting sizes from 1/8 in. to 4 in.: the actual outside diameter, NPT threads per inch, and Schedule 40 and 80 inside diameters, with an example fitting Supply Tie stocks in each size in black or galvanized malleable iron, PVC and brass.

How pipe sizes work

  • Nominal size is not a measurement. A "1/2 in." pipe has an outside diameter of 0.840 in. Measure the outside of the pipe and use the table to find its nominal size.
  • Same size, same outside diameter. Steel, iron and Schedule 40 or 80 PVC pipe of the same nominal size share the same outside diameter; the schedule changes the wall thickness and the inside diameter. Threaded fittings fit threaded steel, iron and Schedule 80 PVC pipe. Schedule 40 PVC should not be threaded and uses solvent-weld (slip) fittings.
  • NPT threads are tapered. National Pipe Taper threads seal as they tighten; use thread sealant or PTFE tape rated for the job (gas-rated sealant on gas lines). MIP/MPT is male thread, FIP/FPT is female thread.
  • Copper and PEX are different. Copper tube and PEX are sized by a different standard, so their outside diameters do not match iron pipe of the same nominal size. Use adapters to join them.

Pipe size chart (1/8 in. to 4 in.)

Nominal size Outside diameter NPT threads per inch Sch 40 inside diameter Sch 80 inside diameter Malleable iron fittings PVC Schedule 40 fittings Brass fittings
1/8 in. 0.405 in (10.3 mm) 27 0.269 in 0.215 in STZ Industries 1/8 in. FIP each X 1/8 in. D FIP 1/8 in. D FIP Black Malleable Iron Tee
19 fittings in this size 		— ATC 1/8 in. FPT X 1/8 in. D MPT Brass 45 Degree Street Elbow
5 fittings in this size
1/4 in. 0.540 in (13.7 mm) 18 0.364 in 0.302 in STZ Industries 1/4 in. MIP each X 1/4 in. D FIP Black Malleable Iron 90 Degree Street Elbow
14 fittings in this size 		— ATC 1/4 in. FPT X 1/4 in. D MPT Brass 45 Degree Street Elbow
12 fittings in this size
3/8 in. 0.675 in (17.1 mm) 18 0.493 in 0.423 in STZ Industries 3/8 in. FIP each X 3/8 in. D FIP Black Malleable Iron 45 Degree Elbow
13 fittings in this size 		— ATC 3/8 in. FPT X 3/8 in. D FPT Brass Tee
8 fittings in this size
1/2 in. 0.840 in (21.3 mm) 14 0.622 in 0.546 in STZ Industries 1/2 in. FIP each X 1/2 in. D FIP 1/2 in. D FIP Black Malleable Iron Side Out Tee
28 fittings in this size 		19 fittings in this size ATC 1/2 in. FIP X 1/2 in. D MIP Brass Street Elbow
10 fittings in this size
3/4 in. 1.050 in (26.7 mm) 14 0.824 in 0.742 in 24 fittings in this size 19 fittings in this size ATC 3/4 in. FPT X 3/4 in. D MPT Brass 90 Degree Street Elbow
6 fittings in this size
1 in. 1.315 in (33.4 mm) 11-1/2 1.049 in 0.957 in 17 fittings in this size Charlotte Pipe Schedule 40 1 in. Slip X 1 in. D Slip PVC Tee 1 pk
18 fittings in this size 		ATC 1 in. MPT Brass Close Nipple
1 fittings in this size
1-1/4 in. 1.660 in (42.2 mm) 11-1/2 1.380 in 1.278 in STZ Industries 1-1/4 in. FIP each X 1-1/4 in. D FIP 1-1/4 in. D FIP Black Malleable Iron Tee
19 fittings in this size 		18 fittings in this size —
1-1/2 in. 1.900 in (48.3 mm) 11-1/2 1.610 in 1.500 in STZ Industries 1-1/2 in. FIP each X 1-1/2 in. D FIP 1-1/2 in. D FIP Black Malleable Iron Tee
20 fittings in this size 		40 fittings in this size —
2 in. 2.375 in (60.3 mm) 11-1/2 2.067 in 1.939 in STZ Industries 2 in. FIP each X 2 in. D FIP 2 in. D FIP Black Malleable Iron Tee
24 fittings in this size 		31 fittings in this size —
2-1/2 in. 2.875 in (73 mm) 8 2.469 in 2.323 in STZ Industries 2-1/2 in. FIP each X 2-1/2 in. D FIP 2-1/2 in. D FIP Black Malleable Iron Tee
12 fittings in this size 		— —
3 in. 3.500 in (88.9 mm) 8 3.068 in 2.900 in STZ Industries 3 in. FIP each X 3 in. D FIP 3 in. D FIP Black Malleable Iron Tee
12 fittings in this size 		Charlotte Pipe Schedule 40 3 in. Slip X 3 in. D Slip PVC Coupling 1 pk
18 fittings in this size 		—
4 in. 4.500 in (114.3 mm) 8 4.026 in 3.826 in STZ Industries 4 in. FIP each X 4 in. D FIP 4 in. D FIP Black Malleable Iron Tee
13 fittings in this size 		15 fittings in this size —

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