Butterfly Valve Size Chart

DN to inches, pipe sizes and valve lengths

Butterfly valves are sized by the nominal diameter (DN) of the pipe they fit, in millimetres, or by the nominal pipe size in inches. DN is a nominal size, not an exact measurement: a DN100 valve fits a 4 inch pipe with an outside diameter of 114.3 mm.

Use the chart below to convert between DN and inches, check your pipe size and see how much space a wafer valve needs between the flanges.

DN (mm)	Inches (NPS)	Steel pipe OD (mm)	Wafer valve face-to-face (mm)	Delivery
DN50	2”	60.3	43	About 10 days
DN65	2½”	76.1	46	About 10 days
DN80	3”	88.9	46	About 10 days
DN100	4”	114.3	52	About 10 days
DN125	5”	139.7	56	About 10 days
DN150	6”	168.3	56	About 10 days
DN200	8”	219.1	60	About 10 days
DN250	10”	273.0	68	About 10 days
DN300	12”	323.9	78	About 10 days
DN350	14”	355.6	78	About 10 days
DN400	16”	406.4	102	Made to order
DN450	18”	457.0	113	Made to order
DN500	20”	508.0	126	Made to order
DN600	24”	610.0	146	Made to order
DN700	28”	711.0	175	Made to order
DN800	32”	813.0	215	Made to order
DN900	36”	914.0	246	Made to order
DN1000	40”	1016.0	280	Made to order
DN1200	48”	1219.0	360	Made to order

Pipe outside diameters are for steel pipe to EN 10220 / ISO 4200; plastic and ductile iron pipes have different outside diameters for the same nominal size. Face-to-face lengths are for Vamein 100 Series wafer valves and are a guide only; please confirm against the valve data sheet before finalising a design.

Need a butterfly valve? We supply the Vamein range from DN50 to DN2000. Sizes up to DN350 are typically delivered in about 10 days from order and payment. Request a quotation or see the Vamein range.

How to Measure for a Replacement Butterfly Valve

Read the body: most valves have the DN size, pressure rating and flange standard cast or marked on the body or label
Measure the pipe: measure the outside diameter of the pipe and find the nearest value in the chart
Count the flange bolts and measure the bolt circle: this identifies the flange standard (PN10, PN16, ANSI 150 or BS 10)
Measure face to face: the gap between the pipe flanges, so the new valve fits without moving pipework
Note the top flange: if the valve has an actuator or gearbox, note the mounting flange (for example F07 or F10) and shaft size

Send us the details, or a photo of the valve and its label, through the quotation form and we will identify a suitable replacement.

Size Questions

What size is a DN100 butterfly valve in inches?

DN100 is 4 inches. It fits steel pipe with an outside diameter of 114.3 mm.

What is DN in valve sizes?

DN stands for diameter nominal, the European nominal size in millimetres. It is close to, but not the same as, the actual bore or outside diameter of the pipe.

How do I convert DN to inches?

Divide by 25 as a rough guide, then use the standard pairs: DN50 = 2 inch, DN80 = 3 inch, DN100 = 4 inch, DN150 = 6 inch, DN200 = 8 inch, DN250 = 10 inch, DN300 = 12 inch.

What sizes do butterfly valves come in?

Vamein butterfly valves are made from DN50 (2 inch) to DN2000 (80 inch). IPT typically delivers sizes up to DN350 in about 10 days from order and payment; larger sizes are made to order.