PipeData

Schedule 40 Pipe Dimensions

Wall thickness, bore and plain-end weight for all 26 sizes ASME B36.10M publishes in schedule 40, NPS 1/8 through NPS 36.

Schedule
Schedule 40
Sizes published
26 (NPS 1/8 to NPS 36)
Thinnest wall
0.068 in (1.7 mm) at NPS 1/8
Thickest wall
0.750 in (19.0 mm) at NPS 36
Standard
ASME B36.10M

Where schedule 40 is used

Schedule 40 is the default wall for carbon steel pipe in general service, and the one most valves, fittings and pipe supports are stocked to suit. In small sizes it is thick enough to thread.

Pipe wall thickness to scale, Schedule 40Pipe cross-sections drawn to scale at the same outside diameter so the wall thicknesses can be compared. NPS 1/8: 0.068 in wall on 0.405 in OD; NPS 5: 0.258 in wall on 5.563 in OD; NPS 36: 0.750 in wall on 36.000 in ODNPS 1/80.068 in wall on 0.405 in ODNPS 50.258 in wall on 5.563 in ODNPS 360.750 in wall on 36.000 in OD
Schedule 40 in three sizes, each drawn to its own scale. The sections are drawn at the same width so that the wall can be compared with the diameter it belongs to. The wall gets thicker as the size goes up, but it takes up a smaller share of the pipe.

Schedule 40 in every size

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

ASME B36.10M schedule 40 dimensions.
SizeDNOutside diameterWall thicknessInside diameterWeight, emptyWater (US gal/ft)This size
NPS 1/8DN 60.40510.29 mm0.0681.73 mm0.2696.83 mm0.240.36 kg/m0.003all schedules →
NPS 1/4DN 80.54013.72 mm0.0882.24 mm0.3649.25 mm0.430.63 kg/m0.005all schedules →
NPS 3/8DN 100.67517.14 mm0.0912.31 mm0.49312.52 mm0.570.85 kg/m0.010all schedules →
NPS 1/2DN 150.84021.34 mm0.1092.77 mm0.62215.80 mm0.851.27 kg/m0.016all schedules →
NPS 3/4DN 201.05026.67 mm0.1132.87 mm0.82420.93 mm1.131.68 kg/m0.028all schedules →
NPS 1DN 251.31533.40 mm0.1333.38 mm1.04926.64 mm1.682.50 kg/m0.045all schedules →
NPS 1 1/4DN 321.66042.16 mm0.1403.56 mm1.38035.05 mm2.273.39 kg/m0.078all schedules →
NPS 1 1/2DN 401.90048.26 mm0.1453.68 mm1.61040.89 mm2.724.05 kg/m0.106all schedules →
NPS 2DN 502.37560.32 mm0.1543.91 mm2.06752.50 mm3.665.44 kg/m0.174all schedules →
NPS 2 1/2DN 652.87573.02 mm0.2035.16 mm2.46962.71 mm5.808.63 kg/m0.249all schedules →
NPS 3DN 803.50088.90 mm0.2165.49 mm3.06877.93 mm7.5811.28 kg/m0.384all schedules →
NPS 3 1/2DN 904.000101.60 mm0.2265.74 mm3.54890.12 mm9.1213.57 kg/m0.514all schedules →
NPS 4DN 1004.500114.30 mm0.2376.02 mm4.026102.26 mm10.8016.07 kg/m0.661all schedules →
NPS 5DN 1255.563141.30 mm0.2586.55 mm5.047128.19 mm14.6321.77 kg/m1.039all schedules →
NPS 6DN 1506.625168.27 mm0.2807.11 mm6.065154.05 mm18.9928.26 kg/m1.501all schedules →
NPS 8DN 2008.625219.07 mm0.3228.18 mm7.981202.72 mm28.5842.53 kg/m2.599all schedules →
NPS 10DN 25010.750273.05 mm0.3659.27 mm10.020254.51 mm40.5260.30 kg/m4.096all schedules →
NPS 12DN 30012.750323.85 mm0.40610.31 mm11.938303.23 mm53.5779.73 kg/m5.815all schedules →
NPS 14DN 35014.000355.60 mm0.43811.13 mm13.124333.35 mm63.5094.50 kg/m7.027all schedules →
NPS 16DN 40016.000406.40 mm0.50012.70 mm15.000381.00 mm82.85123.29 kg/m9.180all schedules →
NPS 18DN 45018.000457.20 mm0.56214.27 mm16.876428.65 mm104.76155.91 kg/m11.620all schedules →
NPS 20DN 50020.000508.00 mm0.59415.09 mm18.812477.82 mm123.23183.38 kg/m14.439all schedules →
NPS 24DN 60024.000609.60 mm0.68817.48 mm22.624574.65 mm171.45255.15 kg/m20.883all schedules →
NPS 32DN 80032.000812.80 mm0.68817.48 mm30.624777.85 mm230.29342.71 kg/m38.263all schedules →
NPS 34DN 85034.000863.60 mm0.68817.48 mm32.624828.65 mm245.00364.60 kg/m43.424all schedules →
NPS 36DN 90036.000914.40 mm0.75019.05 mm34.500876.30 mm282.62420.58 kg/m48.562all schedules →

Weight is plain-end carbon steel, w = 10.69 × t × (OD − t) lb/ft.

How the wall changes with size

The wall in schedule 40 is 0.068 in (1.7 mm) at NPS 1/8 and 0.750 in (19.0 mm) at NPS 36. Measured against the pipe it belongs to, that is 16.8% of the outside diameter at the small end and 2.1% at the large end, so the wall does not keep pace with the diameter. The pressure the pipe will hold moves the same way. On the basis used throughout this site (ASME B31.3, S = 20,000 psi, nominal wall, no corrosion allowance) schedule 40 holds about 7,496 psig at NPS 1/4 and about 823 psig at NPS 34. A schedule is therefore chosen size by size, from a calculation, and not once for a whole plant.

In this schedule the wall thickness coincides with STD in NPS 1/8 through NPS 10 and XS in NPS 16. Outside those sizes it does not, so never substitute one designation for the other without checking the number.

Guides and comparisons for this page

Schedule 40 vs Schedule 80Wall, bore, weight and pressure capacity, size by size.Schedule 10 vs Schedule 40What the lighter wall saves and what it gives up.Schedule 40 vs Schedule 160How far the bore closes up on the heavy wall.What a pipe schedule actually isWhy a schedule is a wall series and not a thickness.Pipe wall thickness calculationBarlow and ASME B31.3, corrosion allowance and mill tolerance.Pipe sizing by flow rate and velocityTurn a flow rate into a line size using velocity limits.

Common questions

What sizes is schedule 40 pipe made in?

ASME B36.10M publishes schedule 40 in 26 sizes, from NPS 1/8 through NPS 36. Wall thickness runs from 0.068 in (1.7 mm) at the small end to 0.750 in (19.0 mm) at the large end.

Does schedule 40 mean the same wall thickness in every size?

No. It is a series, not a thickness. The wall is 0.068 in (1.7 mm) at NPS 1/8 and 0.750 in (19.0 mm) at NPS 36, so the thickness always has to be read off the table for the size in hand.

How pipe schedules work →