Pipe Dimensions — ASME B36.10M

Outside diameter, wall thickness, bore and weight for 30 nominal pipe sizes from NPS 1/8 to NPS 36, across every schedule the standard publishes.

The three dimensions of a pipe. The outside diameter is fixed by the nominal size. The schedule sets the wall, and the inside diameter is what is left. Not to scale.

Dimensions are given in inches, with the millimetre equivalent beneath in grey.

Summary of ASME B36.10M nominal pipe sizes. Standard weight (STD) shown; open a size for every schedule.
Size	DN	Outside diameter	STD wall	STD weight	Schedules
NPS 1/8	DN 6	0.40510.29 mm	0.0681.73 mm	0.240.36 kg/m	8
NPS 1/4	DN 8	0.54013.72 mm	0.0882.24 mm	0.430.63 kg/m	8
NPS 3/8	DN 10	0.67517.14 mm	0.0912.31 mm	0.570.85 kg/m	8
NPS 1/2	DN 15	0.84021.34 mm	0.1092.77 mm	0.851.27 kg/m	9
NPS 3/4	DN 20	1.05026.67 mm	0.1132.87 mm	1.131.68 kg/m	9
NPS 1	DN 25	1.31533.40 mm	0.1333.38 mm	1.682.50 kg/m	9
NPS 1 1/4	DN 32	1.66042.16 mm	0.1403.56 mm	2.273.39 kg/m	9
NPS 1 1/2	DN 40	1.90048.26 mm	0.1453.68 mm	2.724.05 kg/m	9
NPS 2	DN 50	2.37560.32 mm	0.1543.91 mm	3.665.44 kg/m	9
NPS 2 1/2	DN 65	2.87573.02 mm	0.2035.16 mm	5.808.63 kg/m	9
NPS 3	DN 80	3.50088.90 mm	0.2165.49 mm	7.5811.28 kg/m	9
NPS 3 1/2	DN 90	4.000101.60 mm	0.2265.74 mm	9.1213.57 kg/m	7
NPS 4	DN 100	4.500114.30 mm	0.2376.02 mm	10.8016.07 kg/m	10
NPS 5	DN 125	5.563141.30 mm	0.2586.55 mm	14.6321.77 kg/m	9
NPS 6	DN 150	6.625168.27 mm	0.2807.11 mm	18.9928.26 kg/m	9
NPS 8	DN 200	8.625219.07 mm	0.3228.18 mm	28.5842.53 kg/m	14
NPS 10	DN 250	10.750273.05 mm	0.3659.27 mm	40.5260.30 kg/m	14
NPS 12	DN 300	12.750323.85 mm	0.3759.52 mm	49.6173.83 kg/m	14
NPS 14	DN 350	14.000355.60 mm	0.3759.52 mm	54.6281.28 kg/m	13
NPS 16	DN 400	16.000406.40 mm	0.3759.52 mm	62.6493.21 kg/m	13
NPS 18	DN 450	18.000457.20 mm	0.3759.52 mm	70.65105.14 kg/m	13
NPS 20	DN 500	20.000508.00 mm	0.3759.52 mm	78.67117.08 kg/m	13
NPS 22	DN 550	22.000558.80 mm	0.3759.52 mm	86.69129.01 kg/m	12
NPS 24	DN 600	24.000609.60 mm	0.3759.52 mm	94.71140.94 kg/m	13
NPS 26	DN 650	26.000660.40 mm	0.3759.52 mm	102.72152.87 kg/m	4
NPS 28	DN 700	28.000711.20 mm	0.3759.52 mm	110.74164.80 kg/m	5
NPS 30	DN 750	30.000762.00 mm	0.3759.52 mm	118.76176.73 kg/m	6
NPS 32	DN 800	32.000812.80 mm	0.3759.52 mm	126.78188.66 kg/m	6
NPS 34	DN 850	34.000863.60 mm	0.3759.52 mm	134.79200.60 kg/m	6
NPS 36	DN 900	36.000914.40 mm	0.3759.52 mm	142.81212.53 kg/m	6

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Obsolete sizes outside the standard

NPS 4 1/2, 7, 9 and 11 turn up in old plant and on some stock charts, but ASME B36.10 does not publish them, so they are left out of the tables on this site. Each has a page of its own, with dimensions that have not been confirmed against a second source.

NPS 4 1/2 NPS 7 NPS 9 NPS 11

Browse by schedule

Schedule 522 sizes Schedule 1030 sizes Schedule 2015 sizes Schedule 3027 sizes Schedule 4026 sizes Standard (STD)30 sizes Schedule 609 sizes Schedule 8024 sizes Extra Strong (XS)30 sizes Schedule 1009 sizes Schedule 12012 sizes Schedule 1409 sizes Schedule 16023 sizes Double Extra Strong (XXS)17 sizes

Guides and comparisons for pipe

What a pipe schedule actually isWhy a schedule is a wall series and not a thickness.NPS vs DN explainedTwo designators for one pipe, and why neither is a measurement.Pipe sizing by flow rate and velocityTurn a flow rate into a line size using velocity limits.Pipe wall thickness calculationBarlow and ASME B31.3, corrosion allowance and mill tolerance.Schedule 40 vs Schedule 80Wall, bore, weight and pressure capacity, size by size.Seamless vs welded pipeJoint factor, size range and cost.

Common questions

Does the outside diameter of pipe change with schedule?

No. For a given NPS the outside diameter is fixed by ASME B36.10M. Increasing the schedule thickens the wall inward, shrinking the bore while the OD stays put. That is what lets one set of flanges, fittings and pipe supports serve every schedule in a size.

Why does NPS stop matching the actual size above NPS 12?

From NPS 14 up, NPS equals the outside diameter in inches exactly — NPS 14 pipe is 14.000 in OD. Below NPS 14 the number is a historic designator inherited from iron pipe sizing and matches neither the OD nor the bore: NPS 2 pipe is 2.375 in OD.

What is the difference between schedule 40 and standard weight?

They are identical from NPS 1/8 through NPS 10. At NPS 12 they part company — standard weight stays at 0.375 in while schedule 40 goes to 0.406 in — and above NPS 12 standard weight is 0.375 in in every size while schedule 40 keeps climbing.