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Association
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Global O-Ring and Seal has developed these o-ring groove design and gland dimension guidelines to help you size a correct gland for face/flange, static, dynamic and dovetail seals. Use the interactive O-Ring Groove Design Calculator below to apply them in seconds — choose an AS568 series and groove type to get gland depth, width, squeeze and corner radii, with built-in compression, extrusion/pressure and concentricity checks.
Numerous factors go into a gland/groove design — static or dynamic application, pressure, the fluid being sealed, and the tolerances of both the o-ring and the groove — so treat the calculator as a starting point and confirm it against your application. The full design tables, dimensional references and engineering guidance behind the tool are in the Supporting Documentation below.
Groove cut around a piston or shaft; the O-ring is squeezed between the groove bottom and the bore wall. Not sure? Piston/shaft is the most common — pick it and adjust.
Piston / shaft groove — the O-ring is squeezed between the groove bottom and the bore wall. Tap a field below and its dimension lights up.
in
Smaller of the two diameters.
in
Larger of the two diameters.
in
Radial depth. Auto = (OD−ID)÷2.
in
Axial width of the groove.
The finder uses published O-ring design rules — target squeeze (judged by cross-section), gland-fill, and stretch. Inch (AS568) sizes follow the Parker O-Ring Handbook ORD 5700 tables; metric sizes follow ISO 3601-2 (Housing dimensions), with off-standard cross-sections shown as general guidance. Sizes are matched against Global O-Ring’s stocked AS568 and metric sizes. Results are a starting point; final selection should account for tolerances, fluid/thermal swell, pressure, and material. Want a person to confirm it? Request a quote or call 832-448-5550 — most of what we sell is in stock in Houston.
Related: Shop all O-Rings · O-Ring Groove Design guide
Static radial gland — designed clearance gap, no motion.
in
Nearest stocked AS568 dash in this series — with a machine-to-fit tip if your ID is off-standard.
Design Validator
Real-time checks against the methodology described further down this page — compression-ratio extremes, extrusion-pressure limits, and concentric clearance.
Compression Check
Squeeze at nominal dimensions and at both tolerance extremes. Each value is checked against the published squeeze range for the selected series and groove type.
Extrusion / Pressure Check
Enter your application pressure, durometer, and clearance gap. The calculator returns the max safe pressure for that combination (Parker EB-1010 limits) and whether your design fits.
psi
in
Concentricity / Clearance Helper
No measured clearance handy? Enter bore and shaft/piston diameters. Assume all clearance can shift to one side — the full diametric clearance is what the extrusion check needs.
in
in
Extrusion-pressure limits derived from the Parker O-Ring Handbook (ORD 5700 / EB-1010). Values assume continuous pressure at room temperature on elastomeric compounds (Buna-N, FKM/Viton, EPDM). For FFKM, PTFE, polyurethane, high-temperature service, pulsing pressure, or Rapid Gas Decompression, request engineering review.
Sources & standards. Inch gland dimensions and squeeze ranges follow the Parker O-Ring Handbook (ORD 5700) and SAE AS4716: static glands per Design Chart 4-2, face seals per Design Chart 4-3, dovetail glands per the dovetail charts, and dynamic glands per the ORD 5700 reciprocating-seal tables. Cross-section sizes & tolerances per SAE AS568 and ISO 3601-1; metric housing per ISO 3601-2. Extrusion limits per ORD 5700 / Parker EB-1010.
Values are a starting point — the final design must account for tolerance extremes, fluid swell, thermal expansion, and concentricity. Request a quote or call 832-448-5550.
Values are a starting point — the final design must account for tolerance extremes, fluid swell, thermal expansion, and concentricity. Request a quote or call 832-448-5550.
Related: Shop all O-Rings · O-Ring Groove Design guide
Supporting Documentation
Reference tables, dimensional guidance and engineering notes behind the o-ring groove design calculator above.
O-Ring Groove Design Overview
Global O-Ring and Seal has developed o-ring groove design and gland dimension guidelines. These are intended for use in basic design consideration and to understand the core principles involved in o-ring gland/groove design. Numerous factors go into the appropriate design of a gland/groove including but not limited to static or dynamic applications, pressure conditions, fluid characteristics being sealed, and tolerances of both the o-ring and groove.
The calculator at the top of this page applies everything in this guide automatically: enter a measured groove or pick an AS568 size and it returns gland depth, width, squeeze and corner radii, then validates squeeze, extrusion and concentricity. Use the reference below to understand what the tool is calculating — or to design a gland by hand.
Finding the Right O-Ring Cross-Section
The o-ring cross-section in your design will determine all your subsequent dimensions and specifications. Standard o-rings are available in various cross-sections and inside dimensions (ID). For example, an o-ring with an ID of 5 ¼ can be purchased in four standard AS568 cross-sections. Below, is a list of advantages in the selection of smaller and larger cross-section o-rings.
Advantages of Smaller Cross-Section O-Rings
- Compact and lighter-weight o-ring
- Most cost-effective if the design uses expensive elastomers such as FKM or FFKM
- Reduced machining of grooves
Advantages of Larger Cross-Section O-Rings
- Smaller required squeeze to create a seal which reduces compression set issues
- Greater tolerances variations in the machined groove while maintaining acceptable compression squeeze
ID/OD Interference
The ID or OD of the o-ring should be sized to create some interference, per the guidelines below:
- Piston Gland Seals: The ID of the o-ring should be smaller than the OD of the gland so the installed o-ring is always slightly stretched (max 5%)
- Rod Gland Seals: The o-ring OD should be slightly larger than the ID gland depth (max 2%)
- External Pressure Face Seals: The o-ring ID should be slightly smaller than the gland inner diameter (Gland ID) (max 5%)
- Internal Pressure Face Seals: The o-ring OD should be slightly larger than the gland outer diameter (Gland OD) (max 3%)
O-Ring Groove/Gland Types
Below, four standard application groove design guidance tables are presented along with dimensional reference drawings. The first table is for industrial face or flange seals. The second table is for static industrial radial applications. The third table is for dynamic industrial reciprocating applications. Lastly, the fourth table is for dovetail groove design. These o-ring groove design guides offer default dimensional guidance for basic o-ring groove design applications. Pick a seal type in the calculator above to pull these dimensions for any size instantly; the complete reference tables follow.
Flange/Face Seal
A flange or face seal is static and will not have a gap between surfaces, eliminating any design issues associated with extrusion. This is the most straightforward of groove designs.
| AS568 Series | O-Ring Cross-Section | Gland Depth (D) | Squeeze | Gland Width (W) Liquids | Gland Width (W) Vacuum & Gases | Gland Corner Radii | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Nominal | TOL (+/-) | Actual | Percent | Nominal | TOL (+/-) | Nominal | TOL (+/-) | R1 | R2 | ||
| -0XX | 0.070 | 0.003 | .055-0.057 | .010-.018 | 15%-25% | 0.103 | 0.002 | 0.084 | 0.003 | 0.010 | 0.005 |
| -1XX | 0.103 | 0.004 | .088-.090 | .010-.018 | 10%-17% | 0.140 | 0.003 | 0.121 | 0.003 | 0.010 | 0.005 |
| -2XX | 0.139 | 0.004 | .121-.123 | .012-.022 | 9%-16% | 0.180 | 0.003 | 0.160 | 0.003 | 0.018 | 0.005 |
| -3XX | 0.210 | 0.005 | .185-.188 | .017-.030 | 8%-14% | 0.280 | 0.003 | 0.240 | 0.003 | 0.028 | 0.005 |
| -4XX | 0.275 | 0.006 | .237-.240 | .029-.044 | 11%-16% | 0.352 | 0.003 | 0.310 | 0.003 | 0.028 | 0.005 |
Dovetail Face Seal
A dovetail face seal is a special static gland designed to retain the o-ring in the groove. This design is beneficial when the seal is opened and closed during use.
| AS568 Series | O-Ring Cross-Section | Gland Depth (D) | Gland Width (W) | Gland Corner Radii | ||||
|---|---|---|---|---|---|---|---|---|
| Nominal | TOL (+/-) | Nominal | TOL (+/-) | Nominal | TOL (+/-) | R1 | R2 | |
| -0XX | 0.070 | 0.003 | 0.052 | 0.002 | 0.064 | 0.002 | 0.015 | 0.005 |
| -1XX | 0.103 | 0.004 | 0.078 | 0.003 | 0.088 | 0.003 | 0.015 | 0.01 |
| -2XX | 0.139 | 0.004 | 0.106 | 0.003 | 0.120 | 0.003 | 0.031 | 0.01 |
| -3XX | 0.210 | 0.005 | 0.164 | 0.004 | 0.176 | 0.003 | 0.031 | 0.015 |
| -4XX | 0.275 | 0.006 | 0.215 | 0.004 | 0.235 | 0.003 | 0.063 | 0.015 |
Static Gland Seal
A static gland seal is used when two mating components have a designed gap between surfaces. Typically, these applications involve designs involving one mating part being inserted into another part requiring design clearances.
| AS568 Series | O-Ring Cross-Section | Gland Depth (D) | Squeeze | Gland Width (W) | Gap (H) | Gland Corner Radii | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nominal | TOL (+/-) | Actual | Percent | Nominal | TOL (+/-) | w/ 1 Backup Ring | w/ 2 Backup Rings | MAX | R1 | R2 | ||
| -0XX | 0.070 | 0.003 | .050-0.052 | .015-.023 | 22%-32% | 0.095 | 0.002 | 0.140 | 0.207 | 0.002 | 0.007 | 0.005 |
| -1XX | 0.103 | 0.004 | .081-.083 | .017-.025 | 17%-24% | 0.142 | 0.003 | 0.173 | 0.240 | 0.002 | 0.007 | 0.005 |
| -2XX | 0.139 | 0.004 | .111-.113 | .022-.032 | 16%-23% | 0.189 | 0.003 | 0.210 | 0.277 | 0.002 | 0.017 | 0.005 |
| -3XX | 0.210 | 0.005 | .170-.173 | .032-.045 | 15%-21% | 0.283 | 0.003 | 0.313 | 0.412 | 0.003 | 0.027 | 0.005 |
| -4XX | 0.275 | 0.006 | .226-.229 | .040-.055 | 15%-20% | 0.377 | 0.003 | 0.410 | 0.540 | 0.003 | 0.027 | 0.005 |
Dynamic Gland Seal
A dynamic gland seal is used when two mating components are moving in relation to each other while maintaining a seal. There will always be a gap between the two surfaces.
| AS568 Series | O-Ring Cross-Section | Gland Depth (D) | Squeeze | Gland Width (W) | Gap (H) | Gland Corner Radii | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nominal | TOL (+/-) | Actual | Percent | Nominal | TOL (+/-) | w/ 1 Backup Ring | w/ 2 Backup Rings | MAX | R1 | R2 | ||
| -0XX | 0.070 | 0.003 | .055-0.057 | .010-.018 | 15%-25% | 0.095 | 0.002 | 0.140 | 0.207 | 0.002 | 0.007 | 0.005 |
| -1XX | 0.103 | 0.004 | .088-.090 | .010-.018 | 10%-17% | 0.142 | 0.003 | 0.173 | 0.240 | 0.002 | 0.007 | 0.005 |
| -2XX | 0.139 | 0.004 | .121-.123 | .012-.022 | 9%-16% | 0.189 | 0.003 | 0.210 | 0.277 | 0.002 | 0.017 | 0.005 |
| -3XX | 0.210 | 0.005 | .185-.188 | .017-.030 | 8%-14% | 0.283 | 0.003 | 0.313 | 0.412 | 0.003 | 0.027 | 0.005 |
| -4XX | 0.275 | 0.006 | .237-.240 | .029-.044 | 11%-16% | 0.377 | 0.003 | 0.410 | 0.540 | 0.003 | 0.027 | 0.005 |
Groove Design Considerations
The design tables displayed above were created using best practices, including Compression Ratio, O-Ring Extrusion, Concentricity and Diametric Gap, and Backup Rings. The calculator’s Design Validator runs each of these checks for you; the notes below explain the engineering behind them.
Compression Ratio
Our guidelines start with the nominal (or stated) dimension, then incorporate tolerances of the design elements to provide the correct basis for designing the gland/groove. Note: The designer will be making trade-offs between dimensional parameters. Ultimately, the final design must handle the extremes of tolerances.
In the calculation above, we used the nominal (or stated) dimensions. However, when designing the groove, it’s necessary to look at the two extreme cases. First, the o-ring is at its upper tolerance limit and the gland height is at its lower tolerance limit. Secondly, the o-ring is at its smallest cross-section tolerance limit and the gland is at its largest size tolerance limit. These will produce the highest compression and lowest compression percentages. All three compression values must fall between 5%-30% squeeze.
Calculating O-Ring Gland Dimensions
The gland retaining the o-ring has a rectangular area. Once the o-ring cross-section is selected and the gland height is calculated (to achieve the desired squeeze to the o-ring), the final calculation will be the gland width. To find the minimum area necessary, calculate the total volume of the o-ring which creates the rectangle to hold that volume. Below, is the formula to calculate the volume of the o-ring based on the cross-section.
The target gland fill recommendations incorporate several factors that could impact the volume necessary to house the o-ring. These factors include room for thermal expansion, swell due to fluid exposure, and the effect of tolerance variations in the machined groove and molded o-ring.
O-Ring Extrusion
Extrusion is a concern for radial seals where a designed gap exists between moving components: Either the piston and bore, or the rod and bore. The issue is that at higher pressures from one direction, the o-ring can be forced into the small gap and get damaged. The overall design of the sealing system must take into consideration this design gap.
Concentricity and Diametric Gap
In the sealing design, unless the bore and piston (or rod) are ensured to remain concentric by bearings, it must be assumed that all the gap possible can shift to one side. This is the gap used when designing for extrusion.
Design Limits for Extrusion
Many design elements can be used to address extrusion issues in sealing design. If the maximum allowable gap is decreased through alignment/bearings, this allows for an increase in pressure for the same o-ring. Another option is increasing the durometer (hardness) of the compound, which increases the allowable pressure for a defined gap. To read more about the elements involved in o-ring pressure tolerance, click here.
Another alternative is to use backup rings which are anti-extrusion elements. Backup rings are made of thin, hard plastic materials such as Nylon, PTFE, and PEEK. Backup rings work by covering the existing gap. Below, is an extrusion chart providing the pressure limits by gap and durometer of o-ring. If the trade-offs of gap design and durometer do not work, the use of backup rings are recommended to overcome extrusion issues.
Backup Ring Layouts
Backup rings are designed to eliminate the extrusion gap in high-pressure sealing applications. If the pressure is from a single direction, only one backup ring is necessary. If the pressure is from both directions, it’s recommended a backup ring be placed on both sides of the o-ring. The addition of backup rings should be incorporated in the fill calculation for determining the groove width. Finally, backup rings can either be flat (solid, split, or spiral) or contoured.
O-Ring Groove Design: Frequently Asked Questions
What is an o-ring groove (gland)?
An o-ring groove, or gland, is the machined cavity that holds and compresses the o-ring to form a seal. It is defined by its depth, width, and corner radii, and is sized so the o-ring is squeezed by a controlled amount when the mating surfaces close.
How do I calculate o-ring groove dimensions?
Start from the o-ring cross-section, set the gland depth to produce the target squeeze, then size the gland width so the groove is filled to roughly 60-85%. The calculator at the top of this page does this for any AS568 or metric size; the tables in this guide give the standard values for each seal type.
How much should an o-ring be squeezed?
Static seals typically use about 15-30% squeeze, and dynamic seals use less to limit friction and wear. After you account for tolerance extremes, every resulting squeeze value should still fall within the 5-30% range.
How deep should an o-ring groove be?
Gland depth equals the o-ring cross-section minus the intended squeeze. For example, a 0.070-inch cross-section static seal uses a gland depth of about 0.050-0.052 inch, giving 22-32% squeeze. Use the tables above for the depth that matches your AS568 series and seal type.
What is the difference between a static and a dynamic gland?
A static gland seals two parts that do not move relative to each other and can use higher squeeze. A dynamic gland seals moving parts, so it uses lower squeeze, a controlled clearance gap, and closer attention to extrusion and surface finish.
What gland fill percentage should I design to?
Design for roughly 60-85% groove fill, never 100%. The remaining empty volume leaves room for thermal expansion and fluid-induced swell of the elastomer, plus tolerance variation in the machined groove and molded o-ring.
When do I need a backup ring?
Add a backup ring when the combination of clearance gap, system pressure, and o-ring hardness exceeds the extrusion limit. Backup rings are anti-extrusion elements that cover the gap: use one for single-direction pressure and two for pressure from both directions.
What do the gland corner radii (R1 and R2) mean?
R1 and R2 are the small fillet radii at the corners of the groove. Keeping them within the values shown in each table prevents stress concentrations and avoids pinching or cutting the o-ring during installation and use.
