Pipe schedule chart: Sch 40 and Sch 80 sizes, wall thickness and weight (NPS ½" to 24")

Steel pipe schedule chart for NPS ½" to 24": outside diameter, Schedule 40 and Schedule 80 wall thickness and weight per metre to ASME B36.10M, what NPS, DN and schedule mean, and metric EN equivalents.

Updated October 17, 2026

Steel pipe is ordered by nominal size and schedule. The size fixes the outside diameter; the schedule fixes the wall thickness. The chart below gives both for the two most used schedules, Sch 40 and Sch 80, with the weight per metre, so you can check a drawing, a bill of materials or a freight estimate in one place.

NPS, DN and schedule explained

• NPS (nominal pipe size) — the size in inches used in the US system. Up to NPS 12 it is only a name: a 2" pipe is 60.3 mm (2.375 in) outside. From NPS 14 upward the NPS equals the outside diameter in inches.
• DN (diamètre nominal) — the metric size name used in Europe, roughly the bore in millimetres: DN 50 corresponds to NPS 2.
• Schedule (Sch) — a number that sets the wall thickness for each size: Sch 5, 10, 20, 30, 40, 60, 80, 100, 120, 140 and 160. The same schedule gives a thicker wall on a larger pipe.
• STD, XS, XXS — the older weight classes standard, extra strong and double extra strong. STD equals Sch 40 up to NPS 10, and XS equals Sch 80 up to NPS 8; above those sizes they differ.

Schedule 40 and Schedule 80 chart

Weight is calculated as (OD − wall) × wall × 0.0246615 = kg/m, with dimensions in mm. Example: a 6 m length of 4" Sch 40 weighs 16.08 × 6 ≈ 96.5 kg. For other wall thicknesses use the weight calculator.

Sch 40 or Sch 80?

• Sch 40 — the default for water, gas, air and general low-pressure piping, handrails and structural uses of pipe.
• Sch 80 — a thicker wall for higher pressure, threaded joints that remove wall material, abrasion or extra corrosion allowance. It weighs roughly 30–70% more per metre than Sch 40 of the same size.
• The schedule alone is not a pressure rating. The allowable pressure depends on the material grade, temperature, joint type and the piping code your project follows.

ASME and EN outside diameters

European pipe to EN 10220, EN 10255 and EN 10219 uses the same DN steps, but several outside diameters differ slightly from ASME. Check the OD before mixing pipe with fittings or flanges from the other system.

Pipe we supply

• ASTM A53 Grade A — ERW water and gas pipe from NPS ½" to 12", in Schedule 40 throughout, Schedule 80 in NPS 1½" to 2½", 6" and 8", and intermediate walls in NPS 3" to 12". Each size page shows the hydrostatic test pressure of every wall.
• EN 10219 — circular hollow sections in S235JRH to S355J2H for structural use; see the hollow section size tables.

Frequently asked questions

Send your pipe list with sizes, schedules and lengths in a quote request.