Skip to content
ENExplore Calculators

Pipe Size Converter Calculator

Work out pipe size converter instantly with clear inputs, formula shown and shareable results.

About Pipe Size Converter Calculator

Nominal pipe size is a label, not a measurement: 2 inch NPS pipe has a 60.3 mm outside diameter, not 50.8 mm. The outside diameter is fixed per size so that fittings interchange, and the schedule number sets the wall thickness, which eats into the bore. DN 50 is the metric designation for the same pipe.

Formulas

Nominal versus actual

outside diameter is fixed per NPS; schedule sets wall thickness

Bore

inside diameter = outside diameter - 2 x wall thickness

Worked example

With the default values below, Pipe Size Converter Calculator returns Outside Diameter of 60.33. Change any input above and every figure here is recalculated in your browser.

Inputs used

Nominal pipe sizeminimum 0 in
2 in
Wall scheduleone of Schedule 40 (standard), Schedule 80 (extra strong), Schedule 10 (light)
Schedule 40 (standard)

Results

Outside Diameter
60.33 mm
Approximate Inside Diameter
49.94 mm
Approximate Wall Thickness
5.19 mm
Nominal Metric Designation
50 DN

Step by step

  1. 1Values used
  2. 2Nominal versus actual
  3. 3Bore
  4. 4Outside Diameter= 60.33 mm
  5. 5Approximate Inside Diameter= 49.94 mm
  6. 6Approximate Wall Thickness= 5.19 mm
  7. 7Nominal Metric Designation= 50 DN

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does 2 inch pipe measure 60 mm?

The designation originally referred to the bore of thick-walled wrought iron pipe. As walls thinned the outside diameter was frozen so threads stayed compatible.

Does schedule change the outside diameter?

No, only the wall and therefore the bore. That is what allows the same fittings to serve every schedule at a given size.

Related Calculators

Pipe Size Converter Calculator – Calculate Outside Diameter