Pipe Schedule Chart: Sizes, Wall Thickness & Weight

How to read a pipe schedule chart

Pipe is ordered by nominal pipe size (NPS) and schedule. NPS is a name, not a measurement: from 1/8" to 12" the outside diameter is larger than the nominal size, and from 14" up the OD equals the NPS. The OD stays the same for every schedule of a given size, so a higher schedule means a thicker wall and a smaller inside diameter.

Bending pipe? Pipe OD and wall drive your tooling. Enter the OD and wall from this chart in the tube bending calculator to see the degree of bend, wall factor and a mandrel starting point, or browse our tube and pipe benders.

Frequently Asked Questions

What is the difference between Schedule 40 and Schedule 80 pipe?

Both have the same outside diameter for a given NPS. Schedule 80 has a thicker wall, so it has a smaller inside diameter, weighs more and is rated for higher pressure. For 2" pipe, schedule 40 has a 0.154" wall and schedule 80 has a 0.218" wall.

What does the S mean in 10S or 40S?

Schedules ending in S are stainless steel schedules from ASME B36.19M. 40S matches schedule 40 through 10" NPS and 80S matches schedule 80 through 8"; at larger sizes they differ. 5S and 10S are thin-wall schedules used mainly for stainless.

Is STD the same as Schedule 40?

Standard weight (STD) matches schedule 40 from 1/8" through 10" NPS. From 12" up, STD stays at a 0.375" wall while schedule 40 gets thicker. Likewise XS (extra strong) matches schedule 80 through 8".

Why is the outside diameter bigger than the pipe size?

Nominal sizes date back to early iron pipe, when the size described the approximate inside diameter. When walls got thinner the OD was kept so fittings still fit, so 2" pipe has a 2.375" OD.

How do I calculate pipe weight per foot?

For carbon steel, weight in lb/ft = 10.69 × (OD − wall) × wall, with OD and wall in inches. The tube weight calculator does this for other materials and gives total weight for your lengths.