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How To Size a Tri-Clover/Tri-Clamp Fitting


Have you ever wondered how to determin Tri-Clamp size or how to measure a Tri-Clamp fitting? The sizing is based on the outside diameter (OD) of the tube and not on the outside diameter (OD) of the flange end itself. Therefore it is important to note that the OD of the flange end (Or Ferrule Face) does not determine the fitting Size. The OD of the flange end is about ½” wider than the OD of the tubing. Size is based on the Tube OD and not on the Flange OD. For Example a 1.5” Tri-Clover Fitting has a 1.5” OD on the Tube, even though the Flange OD is closer to 2”.

The 1/2" and 3/4" Tri Clamp fittings have the same flange end size of almost 1” (0.984”). This may cause one to think these are the 1” size. Likewise the 1" and 1.5" fittings both have a flange end of almost 2” (1.984"). Again this may cause one to think these are the 2” size.  Furthermore the ½” and ¾” both use a ¾” Clamp. Similarly the 1” and the 1.5” both use a 1.5” Clamp. For Clarification see the Tri-Clamp Sizing Guide table below for Clamp size compared to the actual flange end size.

1) Tube Size (OD)

3) Flange End Size (OD)

2) Tri-Clamp Size

1/2"; 3/4"


3/4" Clamp

1"; 1.5"


1.5" Clamp



2" Clamp



2.5" Clamp



3" Clamp



4" Clamp



6” Clamp

Although the ½” and ¾” will connect with each other as will the 1” and 1.5”, it is important to note that their ID (Internal diameter) will differ. The ID of the ¾” is wider than the ½” and the ID of the 1.5” is wider than the 1”. So it is up to the user to decide if mixing and matching sizes will be suitable for your application. In many cases this could save money and allow you to conveniently jump tube sizes however it could also affect flow, draining and cleaning in a way that may not suit your particular application.

The most popular size used by breweries and for home brewing is the 1” and 1.5” sizes. Since they both have the same flange end size, they can interconnect with each other. For example a 1.5” Tri-Clamp Ball valve will connect with a 1”Ferrule.