Engineering toolkit

DN to NPS converter

Quickly translate between nominal metric and imperial pipe sizes. Use the converter for fast checks, shortlist options with the quick reference table, and share results with suppliers or fabrication teams without losing accuracy.

Quick Converter

Pick your direction and enter the size.

Diameter Nominal

Reference: 1 inch = 25.4 mm. DN values are rounded nominal diameters; always check the pressure class and schedule when sizing for flow or mechanical fit.

Common Conversions

Select Table

DN (Diameter Nominal)(MM)	NPS (Nominal Pipe Size)(INCH)
6	1/8
8	1/4
10	3/8
15	1/2
20	3/4
25	1
32	1 1/4
40	1 1/2
50	2
65	2 1/2
80	3
100	4

DN (Diameter Nominal)(MM)	NPS (Nominal Pipe Size)(INCH)
125	5
150	6
200	8
250	10
300	12
350	14
400	16
450	18
500	20
550	22
600	24

DN (Diameter Nominal)(MM)	NPS (Nominal Pipe Size)(INCH)
6	1/8
8	1/4
10	3/8
15	1/2
20	3/4
25	1
32	1 1/4
40	1 1/2
50	2
65	2 1/2
80	3
100	4
125	5
150	6
200	8
250	10
300	12
350	14
400	16
450	18
500	20
550	22
600	24