Home » Blog » Blog » How To Measure An O-Ring

How To Measure An O-Ring

How To Measure An O-Ring

May 15, 2017

O-Rings are an essential sealing component prolific in every industry, so there’s shapes and sizes to fit nearly every application.

O-Rings: The right size for every occasion

O-rings come in different shapes and sizes. Knowing the measurements an application needs can make a difference on how well an O-ring works. If the O-ring is too big for the application, it will not seal properly. If the O-ring is too small for the application, the seal might break. The performance of an O-ring seal can be optimized by choosing the most appropriate size, which can be found by measuring an O-ring.

How to measure an O-Ring

O-Rings have three different measurements: inside diameter, outside diameter, and cross-sectional thickness.

Inside diameter (I.D.) is measured from one inner border to the other with a measuring device (ruler, measuring tape, PI tape, etc.)

Outside diameter (O.D.) is measured from the outer border to another with a measuring device. However, O.D. is not often used.

Cross-sectional thickness (C.S.) can be measured with calipers or a micrometer. Gently clamp the jaws of the device onto the O-ring to avoid warping it.

If the O-ring is not whole, measure the length of the of the O-Ring and divide by π (3,14), then subtract the cross-sectional thickness.

Length ÷ π = Circumference

Circumference – C.S. = I.D.

Diagram of how to measure the outer dimension and inner dimension of an o-ring

For greater accuracy, it is recommended to use digital measurement equipment. 

For more information about our sealing solutions, check out our Gaskets & O-Rings or contact us for help in your sealing application!

Related Posts

In-Rack Cooling vs In-Row Cooling

In-Rack Cooling vs In-Row Cooling

Data Center Installations: In-Rack Cooling or In-Row Cooling? New artificial intelligence (AI) applications push rapid...

EV Battery Module Types

EV Battery Module Types

Electric vehicle (EV) battery technology drives transformative changes in the automotive industry. Progression in EV...

EV Battery Charger Types

EV Battery Charger Types

Fast, reliable, and safe battery chargers are an essential element to accelerate the adoption of electric vehicles....

Have questions? We’re ready to help!