How to Measure a Gasket

Ring Gaskets

A ring gasket only takes three simple measurements.

I.D. (Inside Diameter)

O.D. (Outside Diameter)

Thickness

Because a ring gasket is round it is best to measure the middle of the gasket. When measuring a circular gasket, think of it as a clock. Use a tape measure or ruler and measure across the gasket from the 9:00 position to the 3:00 position. Measure the inside edges for the I.D. and the outside edges for the O.D. Lastly, measure the thickness using a tape measure or calipers. The most common thicknesses are, 1/16'' and 1/8''. For an example a 1''-150# Ring is (1-5/16'' x 2-5/8'' x 1/16'' Ring)

Full Face Gasket

A full face gasket or FF is similar to a ring gasket except it has holes for bolts in the face of the gasket. It has the following measurements:

I.D. (Outside Diameter)

O.D. (Inside Diameter)

Number of bolt holes (BH) (Evenly Spaced)

Diameter of the bolt center (BC)

Thickness

Because a Full Face is round it is best to measure the middle of the gasket. When measuring a circular gasket, think of it as a clock. Use a tape measure or ruler and measure across the gasket from the 9:00 position to the 3:00 position. Measure the inside edges for the I.D. and the outside edges for the O.D. Next, count the number of BH (Bolt Holes) around the face of the gasket. The holes are usually equally spaced around the gasket (If not please contact us with a picture or drawing and we will be happy to help).
Here comes the tricky measurement, the BC (Bolt Circle). The best way is to position the gasket is so one BH is at 9:00 and the opposite BH is at 3:00. Measure the outside edge of the 9:00 BH and the inside edge of the 3:00 BH. (This means you are measuring the same edge of both Bolt Holes, which is correct. This way eliminates guessing where the middle of the Bolt Hole is.
Lastly, measure the thickness using a tape measure or calipers. The most common thicknesses are, 1/16'' and 1/8''. For an example a 1''-150# FF is (1-5/16'' x 4-1/4'' W/(4) 5/8'' BH on a 3-1/8'' BC)

Obround

An Obround gasket is shaped like a basic race track. It has two straight sides and two 180 degree curves. It has the following measurements:

Short I.D. (Inside Diameter)

Long I.D. (Inside Diameter)

C.S. (Cross Section)

Thickness

The first measurement is the Short I.D. Measure the I.D. of the straight sides.
Next measure the Long I.D. Measure the ID of the 180 Degree curved ends. Make sure you measure the middle of the curve.
Next measure the Cross Section of the gasket also known as the Flange Width. It should be the same size all the way around the gasket.
Lastly measure the thickness of the gasket.
A common example is: 12'' x 16'' x 1/1/4'' x ¼'' Obround

Elliptical

An Elliptical is shaped like an oval or egg. The I.D and O.D. are continuously curving. It has the following measurements:

Short I.D. (Inside Diameter)

Long I.D. (Inside Diameter)

C.S. (Cross Section)

Thickness

The first measurement is the Short I.D. Measure the I.D. at the shortest distance. This is at the middle of the longer curved sides.

Next measure the Long I.D. Measure the ID at the middle of the shorter curved ends.

Next measure the Cross Section of the gasket also known as the Flange Width. It should be the same size all the way around the gasket.

Lastly measure the thickness of the gasket.

A common example is: 12'' x 16'' x 1/1/4'' x ¼'' Elliptical

Other

For a Picture Frame or any other shape, please provide a drawing with dimensions.

Please note: A gasket cannot be properly measured from a scan, fax or copy. Doing so always changes the dimensions.