Steel Pipe Sizes: Outside Diameter, Wall, Bore and Mass

Outside diameter, wall thickness, inside diameter, flow area and mass per metre of standard steel pipe.

Calculated from standard textbook formulas, with every step shown. The formulas are fixed, so the working does not need checking: what matters is the numbers you type in. Use these calculators only if you are competent to choose the inputs (loads, material strength, dimensions, supports) and check your units and assumptions. For learning and checking your own working: design and sign-off are for a qualified engineer. Drafting Central does not store the numbers you type.

How this calculator works

Pipe is sold by nominal size and wall thickness. The nominal size (NPS in inches, DN in millimetres) is not the actual diameter. The outside diameter is fixed for each size, and the wall (the schedule) sets the inside diameter. Schedule 80 has a thicker wall than Schedule 40, so a smaller bore and more mass.

The outside diameters and walls follow ASME B36.10M. Australian pipe to AS 1074 and AS 1163 has its own wall thicknesses, so confirm against the supplier. Steel density 7850 kg/m³ is assumed for the mass.

Formulas used

  • D_i = D_o - 2t
  • A = \frac{\pi D_i^2}{4}
  • m = \rho_s\frac{\pi}{4}(D_o^2 - D_i^2)

Worked example

With the default numbers in the calculator above:

  1. Outside diameter: 88.9 mm
  2. Wall thickness: 5.49 mm
  3. Inside diameter: 77.92 mm
  4. Flow area of the bore: 4769 mm²
  5. Steel mass per metre: 11.29 kg/m
  6. Water mass per metre when full: 4.759 kg/m
  7. Outside surface area per metre: 0.2793 m²/m

Change the numbers in the calculator to see the full working, every step, for your own case.

Common questions

What does DN80 mean?

A nominal diameter of 80 mm, the same pipe as NPS 3. Its outside diameter is 88.9 mm.

What is a pipe schedule?

A number that sets the wall thickness for each nominal size. A higher schedule is a thicker wall.

Does the mass include water?

The steel mass and the mass of water when full are both shown.

Related calculators

Further reading: ASME B36.10M and B36.19M (cited as the source of the sizes only).

Need a calculator we do not have?

Tell us what you would like to calculate. We read every request and build the most asked-for ones.

We store your request (and your email if you give it) to decide what to build. We do not store the numbers you type into calculators.

Embed this calculator on your own page

Copy this code into your page. The calculator runs inside the frame and links back to Drafting Central.

Need this drawn, designed or checked?

Drafting Central is a mechanical engineering and drafting business in Burleigh Waters on the Gold Coast. A calculator gives you the numbers; we can turn them into drawings and designs.

Need help with a real project?

Talk to Drafting Central →

← All engineering calculators