Pipe Schedule Chart — OD, Wall Thickness, ID & Weight (Sch 5 to XXS)

Every carbon-steel size from NPS 1/8 to 36 and every stainless size to NPS 24, with wall thickness, inside diameter, flow area and weight in inches and millimetres. Look a size up, work backwards from a measured OD, or compare all schedules of one size. The whole table is a real HTML table you can scroll on a phone and copy as CSV.

Pipe schedule chart: carbon steel (ASME B36.10M)

Nominal pipe size 1/8 through 36, wall thickness and inside diameter for Sch 5, 10, 40, STD, 80, XS, 160 and XXS, in inches and millimetres. A dash means that schedule is not defined for that size in the standard — it is not a missing value. Sch 40 and STD share a column value up to NPS 10 and Sch 80 and XS up to NPS 8; above that they diverge (see the STD/XS rule). Header and NPS column stay pinned while you scroll.

Schedule 40 pipe dimensions

Schedule 40 pipe has a wall of 0.109 in (2.8 mm) at NPS 1/2, 0.154 in (3.9 mm) at NPS 2, 0.237 in (6.0 mm) at NPS 4 and 0.280 in (7.1 mm) at NPS 6; the outside diameter is the NPS standard OD and the inside diameter is OD minus twice the wall. Weight is plain-end carbon steel from the formulas in the weight section. Sch 40 is not defined at NPS 22, 26, 28 or 30 — STD (0.375 in) is the equivalent stock wall there.

Schedule 80 pipe dimensions

Schedule 80 pipe has a wall of 0.147 in (3.7 mm) at NPS 1/2, 0.218 in (5.5 mm) at NPS 2, 0.337 in (8.6 mm) at NPS 4 and 0.432 in (11.0 mm) at NPS 6 — roughly 40–55% thicker than Sch 40 at the same size, with the same OD and a smaller bore. Sch 80 equals XS up to NPS 8; from NPS 10 up Sch 80 is thicker than the 0.500 in XS wall. It is defined only through NPS 24.

STD, XS and XXS versus Sch 40 and Sch 80

Worked example at NPS 12 (OD 12.750 in): Sch 40 wall is 0.406 in, STD wall is 0.375 in. They are different pipes with different IDs (11.938 in vs 12.000 in) and different weights (53.6 vs 49.6 lb/ft). Any chart that prints one column headed “Sch 40 / STD” is right up to NPS 10 and silently wrong from NPS 12 up. This chart keeps them in separate columns so the divergence is visible: at NPS 10 both read 0.365 in; at NPS 12 they split.

The same happens to Sch 80 versus XS one size earlier: at NPS 8 both are 0.500 in; at NPS 10 Sch 80 is 0.594 in while XS is still 0.500 in.

Stainless steel schedules: 5S, 10S, 40S, 80S (ASME B36.19M)

Stainless pipe uses the same outside diameters as carbon steel but its own schedule series — 5S, 10S, 40S and 80S — with thinner walls at the light end. 40S has the same wall as Sch 40 and 80S the same wall as Sch 80 only through NPS 10; at NPS 12, 40S is 0.375 in (STD) where Sch 40 is 0.406 in, and 80S is 0.500 in (XS) where Sch 80 is 0.688 in. Above NPS 12 the standard defines only 5S and 10S. Note that 5S at NPS 1/2 to 2 is 0.065 in, which is also the Sch 5 carbon wall, but 10S at NPS 14 and up (0.188 in) is thinner than carbon Sch 10 (0.250 in).

Pipe wall thickness chart in mm

Metric-first view of the same data: DN, outside diameter in mm, and wall thickness in mm for every carbon-steel schedule. DN is the ISO nominal size; it is a label like NPS, not a measured bore — DN 50 pipe is 60.3 mm OD, not 50 mm. Values are the inch dimensions from ASME B36.10M converted at 25.4 mm/in and shown to 0.1 mm, which matches how the standard prints its metric columns.

Pipe weight per foot and per metre

Plain-end carbon steel pipe weight comes from the metal cross-section: in inches, lb/ft = 10.69 × (OD − t) × t; in millimetres, kg/m = 0.02466 × (OD − t) × t, where t is the wall thickness. Both constants fold the density of steel (0.2836 lb/in³, 7.85 g/cm³) into π × the annulus area, which is the form the standards use for their listed weights.

• NPS 2 Sch 40: 10.69 × (2.375 − 0.154) × 0.154 = 10.69 × 2.221 × 0.154 = 3.66 lb/ft; in mm, 0.02466 × (60.3 − 3.91) × 3.91 = 5.44 kg/m.
• NPS 4 Sch 40: 10.69 × 4.263 × 0.237 = 10.80 lb/ft (16.07 kg/m).

Stainless is about 1.5% heavier (density 8.0 vs 7.85), so the carbon figures are within rounding for most estimating; the Pipe Weight Calculator handles other materials and total run weight.

How to read a pipe schedule table

Find the row for your nominal size, then the column for your schedule; the cell is the wall thickness, and the inside diameter is the fixed OD for that row minus twice the wall. Three things trip people up:

1. NPS is a name, not a measurement. NPS 2 pipe is 2.375 in (60.3 mm) outside. Only from NPS 14 up does the NPS equal the OD in inches.
2. OD never changes with schedule. Fittings and flanges fit every schedule of one NPS because the outside is constant; only the wall and bore change.
3. Thicker wall = smaller bore. NPS 2: Sch 40 bore 2.067 in, Sch 80 bore 1.939 in, XXS bore 1.503 in — a flow-area drop of 47% from Sch 40 to XXS in the same pipe size.

Worked example: you need the bore of 3-inch Sch 80. Row NPS 3: OD 3.500 in. Column Sch 80: 0.300 in. ID = 3.500 − 2 × 0.300 = 2.900 in (73.7 mm). Flow area = π/4 × 2.900² = 6.605 in².

Worked examples

About this chart

Dimensional values are the nominal wall thickness and outside diameter tables of ASME B36.10M (welded and seamless wrought steel pipe, NPS 1/8–36 here) and ASME B36.19M (stainless steel pipe, NPS 1/8–24). Inside diameter, flow area and weight are computed from those values on this page, not copied from any secondary chart, using unrounded inch values and rounding only for display (3 decimals in inches, 1 decimal in mm, 2 decimals for weight). Wall thickness has a manufacturing tolerance (typically −12.5%) that this chart does not apply.

It does not cover: tube (which is sized by actual OD and gauge), copper tube types K/L/M, PVC or CPVC pressure ratings, DN-series metric pipe that is not an NPS equivalent, schedules 20, 30, 60, 100, 120 and 140 (rare for stock pipe; ask if you need them), or pressure ratings of any kind.

Three frictions this page fixes, from the top results for these queries: (1) the data is usually a PDF or an image, so it cannot be copied or read on a phone — here it is an HTML table with a sticky header, horizontal scroll and a copy-as-CSV button; (2) tables are inches-only or mm-only — every value here is in both; (3) there is no way to go from a measured OD back to a pipe size — the Reverse mode does exactly that, with the delta and the runner-up so you can judge the match. It also keeps Sch 40/STD and Sch 80/XS in separate columns so the divergence above NPS 8–10 is not hidden, and gives flow area and weight, which most charts leave out.