O-Ring Groove & Gland Dimension Charts

Interactive O-Ring gland charts plus design guidelines: male and female radial, face, dovetail, squeeze, gland fill, extrusion gap, surface finish, and installation chamfers.

Filterable gland (groove) dimensions for the styles you machine around an O-Ring. Pick a style chip, search by cross-section, toggle Inch or mm (one unit at a time), and sort any column, the same workflow as the Master Size Chart.

For deeper theory on squeeze, fill, and finish, continue below the chart or see Groove Design.

Static radial (piston / rod)

O-Ring gland dimensions by style and cross-section.
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Surface finish for this style

Ra targets assume about 50% or greater material ratio (tp).

Surface	Duty	Ra (µin)	Rmax (µin)

Pick a gland style chip, then search by CS. Toggle Inch or mm (one unit at a time). Bold / highlighted rows are preferred AS568 cord sizes (0.070, 0.103, 0.139, 0.210, 0.275 in). Chart labels match the diagram: CS (cord), t or h (depth), b (width), z (lead-in), r1 / r2 (radii). Click a column header to sort. For squeeze theory see Groove Design. For dash numbers and ID × CS see the Master Size Chart. Dimensions follow common industrial practice aligned with ISO 3601 preferred cross-sections. Confirm critical fits on your drawing.

How to use the chart

Choose a gland style (static radial, face, dovetail, hydraulic, pneumatic, or floating).
Toggle Inch or mm. The whole table (and surface finish) switches with it.
Search CS in that unit (for example 0.139 or 3.53). Nearest matches sort to the top.
Optionally search depth / width (type a number, or depth 2.9 / width 4.8).
Use AS568 preferred only to show the five common cord sizes. On phones, rows become cards.

Preferred cord sizes (highlighted): 1.78, 2.62, 3.53, 5.33, 6.99 mm (0.070, 0.103, 0.139, 0.210, 0.275 in).

~Squeeze is approximate from cord and groove depth: (CS − depth) / CS. Floating pneumatic rows show none* because depth is greater than the cord on purpose.

Seal types at a glance

Most static O-Ring seals fall into one of three arrangements. A few special cases (triangular, full dovetail, half-dovetail) show up less often.

Male gland (piston)

Male gland seal diagram: O-Ring in a groove on the piston OD

Groove is machined into the OD of the piston. The piston and ring enter the bore. The O-Ring seals radially.

Female gland (rod)

Female gland seal diagram: O-Ring in a groove in the bore ID

Groove is machined into the ID of the bore. A smooth rod is inserted through the ring. The O-Ring seals radially.

Face seal

Groove is machined into a flat face around a hole. A second flat face closes on the ring. The O-Ring seals axially.

Triangular seal

Special V-shaped pocket between two parts. Less common than rectangular male, female, or face glands. Use with care and application testing.

Male, female, and face O-Ring glands with height and width dimension arrows — **Height and width on the three main types.** **Male / female:** width is the groove width; height is the radial squeeze distance (between bore and gland diameter, or gland and rod). **Face:** height is groove depth; width is half the difference between gland OD and ID. Labels in the drawing: **Width**, **Height**, **Bore Ø**, **Gland Ø**, **Piston Ø** / **Rod Ø**, **Gland ID**, **Gland OD**.

Arrangement	Groove location	How it seals
Male gland (piston)	Groove in the OD of the part that enters the bore	Radial
Female gland (rod)	Groove in the ID of the bore; smooth rod goes through the ring	Radial
Face seal	Groove in a flat face around a hole	Axial
Triangular	V-shaped pocket between two parts	Mostly axial / special
Dovetail	Undercut rectangular groove that retains the ring	Axial (see chart style)

Gland height and width (how the chart numbers map)

Every rectangular gland has two pairs of walls:

Sealing surfaces set gland height (depth t or h). Height is less than CS so the ring is squeezed and produces sealing force.
Containing surfaces set gland width (b). Width is greater than CS so the ring has room to spread and the groove is not overfilled.

Seal type	Gland height	Gland width
Male	`(Bore Ø − Gland Ø) / 2`	Groove width machined into the piston
Female	`(Gland Ø − Rod Ø) / 2`	Groove width machined into the bore
Face	Groove depth h	`(Gland OD − Gland ID) / 2`

The interactive chart rows give depth and width for a given CS. Match those to the hardware using the formulas above.

Compression squeeze and ratio

Elastomers bounce back after deformation. That resilience is what makes an O-Ring seal.

Squeeze (length) = CS − gland height. Keep a practical minimum around 0.1 mm (0.005 in) after all tolerances.
Compression ratio (%) = (CS − height) / CS × 100.

Always check stack-up: largest possible ring in the smallest possible groove, and smallest ring in the largest groove. Nominal-only math can hide a seal that under-squeezes at one end of tolerance.

Recommended compression ratio (static, to about 1,500 psi)

Arrangement	Minimum	Target	Maximum
Male or female (radial)	5%	20%	30%
Face (axial)	10%	25%	35%

Dynamic seals usually aim at the lower half of the static band (about 5 to 20%) with tighter hardware, so friction and wear stay manageable. That is why the chart’s hydraulic and pneumatic depths are deeper (less squeeze) than static radial rows.

Gland fill

Diagrams of O-Ring cross-section area and rectangular gland cross-section area — **Left:** O-Ring cross-sectional area uses cord diameter CS (`CSA ≈ π × (CS/2)²`). **Center:** Gland cross-sectional area is roughly **Height × Width** for a rectangular groove. **Right:** Gland fill formula (also shown as text below).

Gland fill is the share of the groove occupied by the ring:

Gland fill (%) = (O-Ring CSA / Gland CSA) × 100

O-Ring CSA ≈ π × (CS/2)²
Gland CSA ≈ Height × Width (rectangular groove)

	Min	Target min	Target	Target max	Max
Gland fill	50%	65%	75%	85%	90%

Leave room for heat growth, media swell, and tolerance stack. Overfill drives extrusion and assembly damage. Underfill can let a dynamic ring roll or leak.

ID / OD interference (stretch and crush)

Pick ring ID/OD so install damage and wear stay low, and the ring is already where pressure will push it.

Seal type	Rule of thumb	Typical limit
Male (piston)	Ring ID slightly smaller than gland OD (light stretch)	About 0 to 5% stretch on ID
Female (rod)	Ring OD slightly larger than gland ID (light interference)	About 0 to 2% on OD
Face, pressure from outside	Ring ID slightly smaller than gland ID	About 0 to 5% on ID
Face, pressure from inside	Ring OD slightly larger than gland OD	About 0 to 3% on OD

Cross-section shrinks when the ring stretches

Rubber is nearly incompressible. Stretch the ID and the cord gets thinner. Use the reduced CS for squeeze and fill math when stretch is non-trivial.

AS568 series	Free CS	~1% stretch	~3%	~5%
0xx	0.070 in (1.78 mm)	0.069 / 1.76	0.068 / 1.74	0.068 / 1.72
1xx	0.103 in (2.62 mm)	0.102 / 2.59	0.100 / 2.56	0.100 / 2.53
2xx	0.139 in (3.53 mm)	0.138 / 3.49	0.136 / 3.44	0.134 / 3.41
3xx	0.210 in (5.33 mm)	0.208 / 5.28	0.205 / 5.20	0.203 / 5.15
4xx	0.275 in (6.99 mm)	0.272 / 6.92	0.268 / 6.82	0.266 / 6.75

Extrusion gap and back-up rings

O-Ring extruded into a diametral clearance gap under pressure — **Extrusion.** System pressure can force rubber into the clearance gap on the low-pressure side. Male gland: gap ≈ Bore Ø − Piston Ø. Female gland: gap ≈ Bore Ø − Rod Ø.

Concentric versus eccentric diametric clearance on radial O-Ring seals — **Concentricity and diametric clearance.** Unless the hardware forces the parts to stay concentric, design as if the full diametric gap can open on one side.

Radial seals have a diametric clearance between piston and bore (male) or rod and bore (female). Face seals usually have metal-to-metal contact, so extrusion gap is less of a story.

Max diametric clearance vs pressure and hardness (guideline)

Values are total diametric clearance (inch, with mm in parentheses).

Pressure (psi)	60 Shore A	70	80	90
500	0.010 (0.25)	0.015 (0.38)	0.020 (0.51)	0.025 (0.64)
750	0.005 (0.13)	0.011 (0.28)	0.016 (0.41)	0.023 (0.58)
1,000	0.002 (0.05)	0.008 (0.20)	0.012 (0.30)	0.018 (0.46)
1,250	0.001 (0.02)	0.004 (0.10)	0.009 (0.23)	0.015 (0.38)
1,500	(tighten or redesign)	0.002 (0.05)	0.007 (0.18)	0.012 (0.30)

Back-up ring installed next to an O-Ring to block extrusion — **Back-up ring.** Used when diametric clearance is too large for the pressure and hardness. The back-up does not seal; it only fills the extrusion gap. Widen the groove by the effective thickness of the back-up.

If you cannot hold those clearances, add a back-up ring on the low-pressure side (or both sides for reversing pressure). See Back-Up Rings and the Master Size Chart AS568 Backup filter.

Groove details: wall angle, radii, finish, chamfer

O-Ring groove with wall angle callout — **Wall angle.** Keep the groove side wall between **0° and 5°** (near-vertical).

O-Ring groove showing mouth radius and bottom radius — **Transition radii.** **Radius 1** is at the groove mouth (edge break into the sealing face). **Radius 2** is at the groove bottom corners. Values by cord size are in the table below.

Transition radii (guideline)

CS range (mm)	CS range (in)	Radius 1 (mm / in)	Radius 2 (mm / in)
1.0–2.0	0.04–0.08	0.10 / 0.004	0.30 / 0.012
2.0–3.0	0.08–0.12	0.20 / 0.008	0.30 / 0.012
3.0–4.0	0.12–0.16	0.20 / 0.008	0.50 / 0.020
4.0–5.0	0.16–0.20	0.20 / 0.008	0.60 / 0.024
5.0–6.0	0.20–0.24	0.20 / 0.008	0.60 / 0.024
6.0–8.0	0.24–0.31	0.20 / 0.008	0.80 / 0.031
8.0–10.0	0.31–0.39	0.20 / 0.008	1.00 / 0.039
10.0–12.0	0.39–0.47	0.20 / 0.008	1.00 / 0.039
12.0–15.0	0.47–0.59	0.20 / 0.008	1.20 / 0.047

The interactive chart r1 / r2 columns follow the style-specific gland tables; use this table when you are laying out a custom groove.

Groove diagram labeling sealing surface A, sealing surface B, and containing surfaces — **Surface finish zones.** **Sealing surface A** is the main contact face. **Sealing surface B** is the groove bottom (or the other contact face). **Containing surfaces** are the groove side walls. Ra targets are in the table below.

Surface finish (Ra)

Surface	Constant pressure (max Ra)	Pulsating pressure (max Ra)
Sealing surface A (main contact)	1.6 µm / 64 µin	0.8 µm / 32 µin
Sealing surface B (groove bottom / other contact)	3.2 µm / 128 µin	1.6 µm / 64 µin
Containing surfaces (groove sides)	6.3 µm / 256 µin	3.2 µm / 128 µin

The finish block under the interactive chart switches with static vs dynamic styles and with the unit toggle.

Male and female installation chamfer diagrams for O-Ring assembly — **Installation chamfer (radial seals).** Use about a **15°** lead-in on the bore or rod. The chamfer must be long enough that the O-Ring only sees the chamfer during install (see length table below). Face seals normally need no install chamfer.

Installation chamfer lengths

O-Ring CS (in / mm)	Min chamfer length (in / mm)
0.070 / 1.78	0.083 / 2.10
0.103 / 2.62	0.122 / 3.10
0.139 / 3.53	0.157 / 4.00
0.210 / 5.33	0.236 / 6.00
0.275 / 6.99	0.283 / 7.20

Install checklist

Do not stretch the ring past its elongation limit.
Deburr edges; blend radii and angles.
Clean chips, dust, and grit before the ring goes in.
Use a compatible lubricant on the ring and/or hardware.
Soft tools only; no sharp edges on sleeves or mandrels.
Do not roll or twist the ring into the groove.

Dimension key

Symbol	Meaning
CS / d2	O-Ring cross-section (cord diameter)
t	Groove depth for radial glands (sets radial squeeze)
h	Groove depth for axial / face / dovetail glands
b / b3	Groove width (room for the flattened ring)
z	Lead-in / chamfer length into the bore or on the piston
r1	Corner radius at the groove mouth
r2	Corner radius at the groove bottom
Gland height	Distance between sealing surfaces (same role as t / h)
Gland width	Distance between containing surfaces (same role as b)

Install stretch and crush (circumference): for radial glands, keep ID stretch about 6% or less, and circumferential crush about 1 to 3%, unless a special design says otherwise. Prefer the largest practical cross-section the hardware allows when tolerances are wide.

Quick design checklist

Pick the style (male, female, face, dovetail, dynamic, floating).
Choose the largest practical CS and a preferred AS568 / ISO size when you can.
Set gland height for squeeze in range; verify min and max stack-up.
Set width for gland fill about 65 to 85% (never over ~90%).
Apply ID/OD interference rules; if stretched, use reduced CS in the math.
Control extrusion gap vs pressure and hardness; add back-up rings if needed.
Spec wall angle, radii, finish, and install chamfer.
Confirm compound on Materials and the Chemical Compatibility Chart.
Test the seal in the real hardware. Guidelines are a start, not a substitute for application testing.

Need a ring that matches a finished groove? Measure the groove, then filter by CS and ID on the Master Size Chart, or contact The O-Ring Store.

Gland dimensions and design limits follow common industrial practice for static O-Ring seals (including ISO 3601 preferred cord sizes and AS568 series). Always verify critical hardware against your print tolerances, pressure, and compound.