O-Ring Groove Chart

O-Ring Groove Design Guide

Squeeze, Stretch & Compression Reference Charts

AS568B & Metric Dimensions • Static & Dynamic Glands • ISO 3601-2 Standards

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How to Use This Guide

A properly designed groove is what makes an O-Ring seal work. The groove controls how much the O-Ring is compressed (the "squeeze"), and that compression is what creates the sealing force. Too little squeeze and it leaks. Too much and the O-Ring wears out fast. This guide gives you the exact groove dimensions for standard AS568B and metric O-Ring sizes across static and dynamic applications.

Quick Rule of Thumb

Static seals use 15% to 30% squeeze. Dynamic seals use 8% to 25%. When in doubt, aim for the middle of the range for your cross-section size.

Static Axial Static Radial Dynamic Metric Key Concepts

Static Axial Face Seal Glands

For seals where the O-Ring is compressed between two flat surfaces with no relative motion. All dimensions in inches.

Key: CS = Cross Section  •  Squeeze % is based on CS  •  All dimensions in inches

Static Radial Seal Glands

For seals compressed radially between a shaft (or plug) and a bore with no relative motion. All dimensions in inches.

Key: CS = Cross Section  •  DC = Diametral Clearance  •  BR = Backup Rings  •  All dimensions in inches

Dynamic Reciprocating Seal Glands

For seals where the shaft or piston moves back and forth through the seal. Lower squeeze percentages reduce friction and wear. All dimensions in inches.

Key: CS = Cross Section  •  DC = Diametral Clearance  •  BR = Backup Rings  •  All dimensions in inches

Important: Dynamic seals use less squeeze than static seals. This reduces friction and heat buildup while still maintaining a reliable seal. If you see extrusion damage, consider adding backup rings.

Metric O-Ring Groove Dimensions

Groove dimensions for metric O-Ring cross-sections. Use the Cylinder columns for piston/rod seals and the Flange columns for face seals. All dimensions in millimeters.

Key: L = Groove Depth  •  G = Groove Width  •  R = Corner Radius  •  All dimensions in millimeters (mm)  •  "–" = Not applicable for this cross-section

Key Groove Design Concepts

Understand the fundamentals behind the numbers in the charts above.

What is O-Ring Squeeze?

Squeeze is the amount an O-Ring is compressed inside its groove. It is expressed as a percentage of the O-Ring's cross-section diameter. For example, a 0.139" cross-section O-Ring with a groove depth of 0.111" has 0.028" of squeeze, which is about 20%. The squeeze creates the contact pressure that forms the seal. ISO 3601-2 provides the standard squeeze ranges, typically 15% to 30% for static seals and 8% to 25% for dynamic seals, depending on cross-section size.

What is O-Ring Stretch?

Stretch is how much an O-Ring is expanded when it is fitted over a shaft or into a bore. Keep stretch to a minimum. For dynamic applications, do not exceed 5%. For vacuum or high-precision static seals, keep it under 2%. Too much stretch thins the cross-section, reduces squeeze, and can cause spiral failure or premature wear.

What is Gland Fill?

Gland fill is the percentage of the groove volume that the O-Ring occupies when installed. A good design targets 60% to 85% gland fill. This leaves room for thermal expansion and prevents the O-Ring from being pinched or extruded. If gland fill exceeds 90%, the O-Ring has no room to move and will fail early. The groove width dimensions in the charts above are designed to keep gland fill within these safe limits.

When Do I Need Backup Rings?

Backup rings prevent O-Ring extrusion in high-pressure applications. When system pressure pushes the O-Ring into the diametral clearance gap, a backup ring supports it and blocks extrusion. Use one backup ring on the low-pressure side for pressures up to approximately 1,500 PSI. Use two backup rings (one on each side) for pressures above 1,500 PSI or when pressure can come from either direction. The groove width must be wider to accommodate backup rings, as shown in the "1 BR" and "2 BR" columns in the charts above.

Disclaimer: The information on this page is believed to be accurate and reliable. However, The O-Ring Store LLC makes no warranty, expressed or implied, that parts supplied using this data will perform satisfactorily in specific applications. It is the customer's responsibility to evaluate the material and design prior to use. For critical or custom applications, email our team for assistance.

Need Help With Your Groove Design?

Our team can help you select the right O-Ring size, material, and groove dimensions for your application.

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