convertimate Pipe sizes (NPS, DN)

Nominal diameter to outside diameter in mm

Type a value in DN to get it in mm OD instantly.

33.4mm OD

That's about the same as a 1" gas line.

What it means

How big is that pipe?

Steel pipe to ASME B36.10 / ISO 6708. The outside diameter is the same for every schedule; the wall, and so the bore, changes. Copper tube and PVC have their own sizes.

The math

How to convert DN to mm OD

Pipe sizes are a table: NPS 2 = DN 50 = 60.3 mm (2.375 in) OD, NPS 4 = DN 100 = 114.3 mm. From NPS 14 the OD equals the NPS in inches.

Example: DN 25 DN = 33.401 mm OD.

Every unit

That pipe in every system

Tables

DN to mm OD conversion table

DN to mm OD conversion table
DNmm OD
DN 6 DN10.287 mm OD
DN 8 DN13.716 mm OD
DN 10 DN17.145 mm OD
DN 15 DN21.336 mm OD
DN 20 DN26.67 mm OD
DN 25 DN33.401 mm OD
DN 32 DN42.164 mm OD
DN 40 DN48.26 mm OD
DN 50 DN60.325 mm OD
DN 65 DN73.025 mm OD
DN 80 DN88.9 mm OD
DN 100 DN114.3 mm OD
DN 125 DN141.3 mm OD
DN 150 DN168.275 mm OD
DN 200 DN219.075 mm OD
DN 250 DN273.05 mm OD
DN 300 DN323.85 mm OD
DN 350 DN355.6 mm OD
DN 400 DN406.4 mm OD
DN 450 DN457.2 mm OD
DN 500 DN508 mm OD
DN 600 DN609.6 mm OD
mm OD to DN conversion table
mm OD to DN conversion table
mm ODDN
10.3 mm ODDN 6 DN
13.7 mm ODDN 8 DN
17.1 mm ODDN 10 DN
21.3 mm ODDN 15 DN
26.7 mm ODDN 20 DN
33.4 mm ODDN 25 DN
42.2 mm ODDN 32 DN
48.3 mm ODDN 40 DN
60.3 mm ODDN 50 DN
73 mm ODDN 65 DN
88.9 mm ODDN 80 DN
114 mm ODDN 100 DN
141 mm ODDN 125 DN
168 mm ODDN 150 DN
219 mm ODDN 200 DN
273 mm ODDN 250 DN
324 mm ODDN 300 DN
356 mm ODDN 350 DN
406 mm ODDN 400 DN
457 mm ODDN 450 DN
508 mm ODDN 500 DN

Quick answers

Quick answers

How many mm OD is DN 10 DN?
DN 10 DN is 17.145 mm OD.
How many mm OD is DN 25 DN?
DN 25 DN is 33.401 mm OD.

The units

About these units

Nominal diameter (DN)

The metric nominal size: DN 15, 25, 50…

Outside diameter in mm (mm OD)

The actual outside diameter in millimeters.

Learn more about pipe units

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