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O-ring groove & gap calculator

Size an O-ring gland per ISO 3601: pick the seal configuration and cross-section, and get the recommended squeeze, groove width and depth, gland fill, and the maximum diametral clearance before extrusion. Radial (rod/piston, static or dynamic) and axial / face seals.

Gland cross-section Radial static

Seal configuration

Cross-section d₂ ISO 3601

Custom d₂ mm

System pressure MPa

Hardness Shore A

Back-up rings

Sealing / bore Ø mm · optional

O-ring inner Ø d₁ mm · optional

Actual diametral clearance mm · optional, to check

Engineering notes

Method

Squeeze (compression) targets: radial static 15–27 %, radial dynamic 8–16 %, axial / face 15–30 %. Groove depth t = d₂ · (1 − squeeze).
Groove width b follows ISO 3601-2 housings for the standard sections; back-up rings widen it.
Gland fill = O-ring section area / groove area. Keep ≤ 85 % (max 90 %) so the ring has room for thermal expansion and media swell.
Extrusion gap: maximum diametral clearance before the ring extrudes, from pressure + hardness (no back-up). Back-up rings allow a much larger gap.

Sources

ISO 3601-1 (sizes) and ISO 3601-2 (housing dimensions). Extrusion limits are a typical guideline — verify against your O-ring supplier's chart and the controlled standard for production.

Result

Live