O-Ring Groove Calculator for Radial Static Seals
Calculate squeeze, stretch and gland fill for a radial static O-ring seal across nominal and tolerance-limit conditions.
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Calculator guidance and result interpretation
What this calculator solves
Use this calculator to check whether a piston or rod static-seal groove gives the selected O-ring enough compression without excessive stretch or gland fill.
When to use it
- •Static piston seals in housings
- •Static rod, plug and tube joints
- •Early groove sizing and drawing review
Worked example: why tolerance limits matter
For an illustrative 3.00 ± 0.05 mm free cross-section and 2.40 ± 0.05 mm assembled gland height, the nominal geometric squeeze is (3.00 − 2.40) / 3.00 = 20.00%. At the opposing tolerance limits it ranges from (2.95 − 2.45) / 2.95 = 16.95% to (3.05 − 2.35) / 3.05 = 22.95%.
This is a squeeze-only illustration, not a seal qualification. The full calculator also accounts for installation stretch, groove geometry, material effects and the active acceptance criteria.
Input parameters
- O-ring size
- Inside diameter, cross-section and their tolerances, or a standard/supplier size candidate.
- Gland geometry
- Bore, rod or piston dimensions plus groove depth and width at tolerance limits.
- Operating conditions
- Pressure, temperature, material hardness and expected media swell.
How to read the results
- Read minimum squeeze first: too little compression can lose sealing contact at the worst tolerance condition.
- Review maximum squeeze and gland fill together: both rise with the largest cord and the smallest available gland.
- ID stretch shows whether assembly tension is changing the cord cross-section enough to affect the result.
Engineering considerations
- Use diametral clearances that include machining tolerance, eccentricity and pressure expansion.
- An unqualified result does not block report export; the report retains the failed criterion and engineering context.
- Confirm final groove dimensions against the selected standard and compound supplier data.
Related tools and engineering resources
Frequently asked questions
How is O-ring squeeze calculated?
Squeeze is the reduction in free cross-section divided by the free cross-section, expressed as a percentage. This tool repeats the calculation at the governing tolerance limits.
Should I use piston or rod geometry?
Choose the geometry that matches where the groove is located. A piston groove seals against a bore; a rod or housing groove seals against a shaft or plug.