Metric O-Ring Size Chart

The metric O-ring size chart defines O-ring dimensions in millimeters and is widely used in Europe and international industrial applications. Metric O-rings are commonly manufactured according to ISO and DIN standards.

What Are Metric O-Rings?

Metric O-rings are sized using millimeter-based measurements, including inner diameter (ID) and cross section (CS). Unlike inch-based AS568 O-rings, metric O-rings are typically specified according to ISO 3601 or DIN 3771 standards.

• Dimensions defined in millimeters (mm)
• Common in European and global markets
• Compatible with ISO and DIN sealing systems
• Available in a wide range of elastomer materials

Metric O-Ring Size System Overview

A metric O-ring size is typically expressed as:

Inner Diameter (ID) × Cross Section (CS) (for example: 20 × 2.5 mm)

• ID: Inner diameter of the O-ring
• CS: Cross-sectional thickness
• OD: Outer diameter = ID + 2 × CS

Common Metric O-Ring Standards

• ISO 3601 O-Rings
• DIN 3771 O-Rings

How to Measure Metric O-Rings

• Measure the inner diameter (ID) in millimeters
• Measure the cross section (CS)
• Confirm groove dimensions for proper sealing

Available Materials for Metric O-Rings

Metric O-rings can be produced in various elastomer materials depending on temperature, chemical exposure, and pressure requirements:

• NBR (Buna-N) O-Rings
• FKM (Viton®) O-Rings
• EPDM O-Rings
• Silicone O-Rings
• FFKM O-Rings

Typical Applications

• Hydraulic and pneumatic systems
• Industrial machinery
• Automotive and heavy equipment
• Oil and gas sealing applications

Custom Metric O-Rings & Bulk Supply

We manufacture metric O-rings in standard and custom dimensions, materials, and hardness. Bulk orders and OEM projects are supported with strict quality control.

Need inch-sized alternatives? View our AS568 O-Ring Size Chart for inch standard O-rings.