Pipe Size Converter
Enter a pipe size and instantly convert NPS inches to DN and actual mm diameter.
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How to use
- Enter your value in the box above or select an option.
- The result updates live right away — no button needed.
- Change the value or unit and the new result shows automatically.
Note
NPS (Nominal Pipe Size) is a name, not the actual diameter — for example, an NPS 1/2 pipe has an outside diameter of 21.3 mm, not 12.7 mm. DN (Diameter Nominal) is the metric name for the same size.
Frequently Asked Questions (FAQ)
What does the Pipe Size Converter do?
Select a pipe size to instantly convert between NPS inches, DN and the actual diameter in millimetres.
Is NPS the actual pipe diameter?
No. NPS is a name, not the actual diameter. For example, an NPS 1/2 pipe has an outside diameter of 21.3 mm, not 12.7 mm, while DN is the metric name for the same size.
What does the result show?
The selected size as NPS = DN, together with the actual diameter in millimetres.
Do I need to press a button to calculate?
No. The result updates live as soon as you pick a size from the dropdown.