O-Ring Groove & Compression Calculator

Calculate O-ring squeeze percentage for static, dynamic and rotary groove designs

Use this free O-ring squeeze calculator to verify compression before you machine a groove or order seals. Enter cross-section (CS) and groove depth to calculate O-ring compression as a percentage, then compare against the standard 15–25% range for static seals and 10–20% for dynamic hydraulic service. It doubles as an O-ring gland calculator: rearrange the result to size groove depth for a complete gland layout. Works in inch or millimeter units — pair with our O-ring specification chart and groove design guide for detailed gland dimensions and tolerances.

O-ring compression formula

Compression % = (CS − Groove Depth) ÷ CS × 100

Groove Depth = CS × (1 − Compression % ÷ 100)

Inputs

O-ring Cross Section (CS)

Groove Depth (GD)

O-ring Inside Diameter (optional)

Groove Inside Diameter (optional)

Results

Enter cross section and groove depth to see results.

Reference Table

Application	Compression
Static seal	15% – 25%
Dynamic seal	10% – 20%

Groove Design Recommendations

Groove width = 1.1 to 1.3 × O-ring cross section
Static seal surface finish: 16 – 32 μin Ra
Dynamic seal surface finish: 8 – 16 μin Ra
Maximum stretch during installation: ≤ 6%
Lead-in chamfers: 15° – 20° to prevent cutting

Related Engineering Resources

O-Ring Squeeze Calculator FAQ

Common questions about using this free O-ring squeeze calculator as a gland calculator: verifying compression percentage, groove depth and groove fill for static, dynamic and rotary seal designs.

What is the correct compression rate for a static O-ring seal?

For static seals (no relative motion), the recommended compression rate is 15–25%. Insufficient compression (below 15%) risks leakage; excessive compression (above 30%) accelerates compression set and may cause extrusion.

What compression rate should I use for dynamic hydraulic seals?

For reciprocating dynamic seals (piston and rod seals in hydraulic cylinders), use 10–20% compression. Lower compression reduces friction and heat generation; higher compression improves sealing force.

How do I calculate groove depth from compression rate?

Rearrange the formula: Groove depth = CS × (1 - compression_rate/100). For example: AS568-214 with CS = 3.53mm at 20% compression: groove depth = 3.53 × 0.80 = 2.82mm.

Does compression rate change with O-ring material?

The recommended compression rate range is the same across materials. However, harder materials (higher Shore A) require more force to achieve the same compression, and softer materials are more sensitive to over-compression.

How do I calculate O-ring compression rate?

Compression rate = ((Cross-Section - Groove Depth) / Cross-Section) × 100. Enter your CS and groove depth into the calculator to verify your design.

How do I calculate O-ring compression from groove depth?

Divide groove depth by cross-section (CS), subtract from 1, and multiply by 100. Example: CS = 2.65 mm, groove depth = 2.12 mm → compression = ((2.65 − 2.12) / 2.65) × 100 = 20%. Use this free calculator to check static (15–25%) and dynamic (10–20%) ranges instantly.

Is this O-ring compression calculator free to use?

Yes. The calculator is free for engineers and procurement teams. Enter cross-section and groove depth in inch or millimeter units, verify squeeze percentage, and request a quote with your dimensions pre-filled.