O-Ring Tools

O-Ring Groove Calculation

Almost all O-ring failures come down to poorly designed grooves. Choose the seal type and cord thickness and the tool returns the matching groove dimensions as reference values based on ISO 3601.

← All O-Ring Tools

Calculate groove

Input · O-ring

Inner diameter d1

Tolerance d1: after input

Cord thickness d2

Tolerance d2: after input

Pressure direction

Result · groove

Groove inner diameter

Groove width (b)

Groove depth static (t)

Groove depth dynamic (t)

ISO 3601

All values in millimetres. Tolerances per ISO 3601-1, class B (cord thicknesses above 8.4 mm are not standardised there), groove dimensions as reference values based on ISO 3601-2. Intermediate sizes are interpolated between the table values. For the flange seal the groove inner diameter follows the selected pressure direction. For the piston seal the O-ring sits on the groove bottom with 2% stretch (dynamic 3% at most, static 5% at most). For the rod seal it rests against the groove bottom on the outside and is compressed there by 3% at most. All values are application-dependent reference values.

Disclaimer

This tool provides non-binding reference values as a design aid based on ISO 3601. We accept no liability for the accuracy, completeness or suitability of the values in a specific application. The respective data sheet always prevails. Please verify the design on your own responsibility and consult us in case of doubt. Liability for damages arising from the use of this tool is excluded to the extent permitted by law.

Good to know

How do I use the groove calculation?

There are two starting points. 1. You know your O-ring and need the matching groove: choose the cord thickness and the tool shows groove width and depth. 2. You know your groove and need the matching O-ring: enter groove width or depth, the tool fills in the second value and names the matching cord thickness. For piston and rod seals it checks whether the groove depth fits a static or a dynamic groove. The input is then locked; use the ✕ in the field to start a new calculation. If you need support, just get in touch.

Which materials does the groove calculation apply to?

Suitable for FFKM (ECOLAST), FKM, NBR, HNBR, EPDM, silicone, FVMQ, FEPM, CR and ACM. Notes: PTFE- and FEP-encapsulated O-rings should only be used as a flange seal. PTFE O-rings have their own table values and therefore a separate groove calculation, see the "PTFE O-rings" tab.

What is a flange seal?

Flange seals are compressed axially by rigidly bolting a cover to the flange. Two pipe flanges can also be sealed together this way. These are stationary, static seals.

What is a piston seal?

The groove is in the inner part, for example of a piston, and the O-ring is compressed radially (compression line 90° to the axis). Piston seals are common in hydraulic cylinders and are mostly used dynamically. The O-ring is stretched slightly onto the groove bottom so that it sits firmly and does not twist during the stroke: 2% as a guide, 3% at most for dynamic and 5% at most for static use.

What is a rod seal?

The groove is in the outer part, for example the cylinder head, and the O-ring seals on the inside against the rod, compressed radially. Rod seals are used above all in moving, dynamic seals. The O-ring rests against the groove bottom on the outside and is compressed slightly there, 3% at most. Its inner diameter roughly matches the rod diameter.

Difference between static and dynamic?

Static sealing means no movement, dynamic sealing means movement. Dynamic installation spaces are designed slightly deeper.

Disclaimer, errors and changes

Errors and changes excepted. The stated values are non-binding and serve as a recommendation. For more detailed questions reach us at info@nh-oring.de.

Unsure about the design?

Send us your installation situation and the desired material. We help with groove, cord thickness and material choice, with no minimum order and no tooling costs.

Request now →

O-ring groove dimensions: installation space by cord thickness

Recommended groove width (GW) and groove depth (GD) per cord thickness, separated by seal type and static or dynamic use. All dimensions in millimetres, reference values for the design.

Cord thickness mm	Flange seal		Piston seal				Rod seal
	static		static		dynamic		static		dynamic
	GW	GD	GW	GD	GW	GD	GW	GD	GW	GD
1.00	1.90	0.70	1.58	0.70	1.58	0.85	1.58	0.70	1.58	0.85
1.50	2.80	1.10	2.19	1.05	2.19	1.27	2.19	1.05	2.19	1.27
1.78	3.20	1.30	2.53	1.30	2.53	1.50	2.53	1.30	2.53	1.50
2.00	3.40	1.50	2.78	1.50	2.78	1.65	2.78	1.50	2.78	1.65
2.50	3.90	1.90	3.37	1.90	3.37	2.12	3.37	1.90	3.37	2.12
2.62	4.00	2.00	3.51	2.00	3.51	2.22	3.51	2.00	3.51	2.22
3.00	4.60	2.30	3.98	2.30	3.98	2.55	3.98	2.30	3.98	2.55
3.53	5.30	2.70	4.67	2.70	4.67	2.95	4.67	2.70	4.67	2.95
4.00	6.00	3.10	5.23	3.10	5.23	3.30	5.23	3.10	5.23	3.30
4.50	6.50	3.50	5.90	3.50	5.90	3.80	5.90	3.50	5.90	3.80
5.00	7.40	3.90	6.48	3.90	6.48	4.30	6.48	3.90	6.48	4.30
5.33	7.60	4.20	6.86	4.20	6.86	4.60	6.86	4.20	6.86	4.60
5.50	7.60	4.40	7.05	4.40	7.05	4.80	7.05	4.40	7.05	4.80
6.00	8.00	4.80	7.59	4.80	7.59	5.20	7.59	4.80	7.59	5.20
6.50	8.40	5.30	8.17	5.30	8.17	5.60	8.17	5.30	8.17	5.60
7.00	8.70	5.70	8.68	5.80	8.68	6.00	8.68	5.80	8.68	6.00
7.50	9.50	6.20	9.29	6.30	9.29	6.50	9.29	6.30	9.29	6.50
8.00	9.80	6.70	9.88	6.80	9.88	7.00	9.88	6.80	9.88	7.00
9.00	11.20	7.60	11.14	7.70	11.14	7.90	11.14	7.70	11.14	7.90
10.00	12.20	8.60	12.38	8.60	12.38	8.80	12.38	8.60	12.38	8.80

GW groove width · GD groove depth · all values in mm. Reference values for groove design; material, tolerances and operating conditions prevail. Check dimensions with our O-Ring Groove Calculation.