NPS & Schedule Calculator

Quickly find pipe outer diameter (OD) and wall thickness (WT / THK) based on Nominal Pipe Size (NPS) and Schedule (SCH) according to ASME standards. This tool is essential for piping design, procurement, and engineering calculations.

NPS & Schedule
Calculator

NPS
DN
SCH
Technical Specifications (OD × Wall THK, Unit: mm)
- × -
Standard reference: ASME B36.10M / B36.19M
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1. Nominal Pipe Size (NPS)

Select the Nominal Pipe Size (NPS):

  • Standard sizes: 1/8″, 1/4″, 1/2″, 1″, 2″, etc.
  • NPS is a nominal designation, not the actual diameter

👉 Example:
NPS 1/2 ≠ 0.5 inch actual OD

2. Nominal Diameter (DN)

Select the DN (metric equivalent):

  • DN is expressed in millimeters
  • Used in ISO / European standards

👉 Example:

  • NPS 1/2 → DN 15
  • NPS 1 → DN 25

3. Pipe Schedule (SCH)

Select pipe schedule:

  • Indicates wall thickness
  • Common values:
    • SCH 10 (thin wall)
    • SCH 40 (standard)
    • SCH 80 (thick wall)

Output

Pipe Dimensions Result

👉 OD × Wall Thickness (mm)
Example:
10.29 × 1.73 mm

Selected Parameters

  • NPS: 1/8
  • DN: 6
  • SCH: 40

Standard Reference

ASME B36.10M / ASME B36.19M

Quick Reference Table

NPS DN OD (mm) SCH 40 (mm) SCH 80 (mm)
1/8 6 10.29 1.73 2.41
1/4 8 13.72 2.24 3.02
1/2 15 21.34 2.77 3.73
1 25 33.40 3.38 4.55
2 50 60.33 3.91 5.54

How to Use This Calculator

  1. Select NPS (inch size)
  2. Select corresponding DN (metric size)
  3. Choose Schedule (SCH)
  4. Instantly get:
    • Outer Diameter (OD)
    • Wall Thickness (WT)

✔ Real-time lookup
✔ Based on ASME standards

Common Engineering Uses

1. Piping System Design

  • Determine correct pipe dimensions

2. Procurement & Sourcing

  • Match international pipe standards

3. Pressure Calculations

  • Wall thickness affects pressure rating

4. Fabrication & Welding

  • Ensure compatibility between pipes

Important Notes

  • NPS is not equal to actual OD
  • OD is fixed for each NPS
  • Wall thickness varies by schedule

👉 Always confirm:

  • Material standard (carbon steel vs stainless)
  • Applicable code (ASME / ISO)

Related Tools

  • Pipe Weight Calculator
  • Density Calculator
  • Material Grade Finder
  • Press Fit Calculator

FAQ

What is NPS?

Nominal Pipe Size used in North America.

What is DN?

Metric equivalent of pipe size.

What does Schedule mean?

It defines pipe wall thickness.

Why is OD constant?

OD is standardized for compatibility.

Which standard is used?

ASME B36.10M (carbon steel) and B36.19M (stainless steel).

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