Huiya · Technical Reference

DN to Inch Pipe Size Chart — with mm OD across Metric, ANSI Sch 80 & JIS

Convert DN to inch and back, and read the real outside diameter (OD) in mm for the same nominal size under three plastic-pipe standards: metric/DIN, ANSI Schedule 80, and JIS. Type any size below, or read the full pipe size chart (inch and mm) further down.

Pipe size converter

Enter an inch size, DN, metric dn or an OD in mm — e.g. 2″, DN50, dn63 or 60.

Metric / DIN

mm OD (dn)

ANSI Sch 80

mm OD

JIS

mm OD

Plastic pipe size chart — inch, DN and OD (mm)

Nominal sizeinch / DN	Metric / DINOD mm (dn)	ANSI Sch 80OD mm	JISOD mm
3/8″DN10	16	17.14	18
1/2″DN15	20	21.34	22
3/4″DN20	25	26.67	26
1″DN25	32	33.4	32
1-1/4″DN32	40	42.16	38
1-1/2″DN40	50	48.26	48
2″DN50	63	60.33	60
2-1/2″DN65	75	73.03	76
3″DN80	90	88.9	89
4″DN100	110	114.3	114
5″DN125	140	141.3	140
6″DN150	160	168.28	165
8″DN200	225	219.08	216
10″DN250	280	273.05	267
12″DN300	315	323.85	318

Nominal outside diameter shown in mm; tolerances vary by standard, schedule and pressure class. Metric values follow the DIN/ISO dn series (also used in GB). ANSI Sch 40 and Sch 80 share the same OD. Always confirm dimensions against the governing standard for pressure-critical work.

How to read this chart (and why the standards don’t interchange)

A “2-inch” pipe, DN50 and dn63 all describe the same nominal size — but the actual outside diameter is not the same in every system. Metric/DIN pipe is named by its OD, so a dn63 pipe really is 63 mm across. ANSI (inch-based) pipe of the same nominal 2″ measures about 60.3 mm, and JIS lands near 60 mm. The nominal name matches; the millimetres do not.

That gap is why pipe and fittings from different standards do not bolt or solvent-weld together reliably: the diameters, and on flanged ends the bolt circles, simply differ. The practical rule is to keep pipe, fittings and valves on a single standard end to end, and to use this chart only to identify the nearest equivalent — not as a licence to mix systems.

Pipe size FAQ

Is DN the same as inch?

No. DN (diamètre nominal) is a metric label and inch (NPS) is the imperial label for the same nominal size — DN50 corresponds to 2″, DN100 to 4″, and so on. They are matching names, not equal measurements: the true OD in mm still depends on the standard, as the chart above shows.

What is DN50 in inches?

DN50 is the nominal equivalent of 2 inch. The OD is about 60.3 mm under ANSI, 60 mm under JIS, and 63 mm for metric/DIN dn63 pipe.

Is dn63 the same as 2 inch pipe?

By nominal size, yes — metric dn63 = DN50 = 2″. By outside diameter, not exactly: dn63 is 63 mm, while a 2″ ANSI pipe is ~60.3 mm. So a dn63 pipe will not fit a 2″ imperial fitting.

Does metric pipe fit ANSI or JIS fittings?

Generally no. The outside diameters differ by a few millimetres, and flanged connections have different bolt circles, so different standards are not interchangeable without an adapter or a transition fitting. Match everything to one standard.

What is the OD of 2 inch PVC pipe?

About 60.3 mm for ANSI Schedule 40/80 (they share the same OD). For metric/DIN it is 63 mm (dn63) and for JIS roughly 60 mm.

Need pipe, fittings or valves in a specific standard?

We manufacture UPVC, CPVC, PPH and PVDF pipe, fittings and valves to ANSI Schedule 80, DIN PN and JIS. Send your size, material and media and our engineers will spec the exact match.

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