Reference Table
O-Ring Sizes Reference
Standard AS568 O-ring sizes — inside diameter and cross-section for the most common O-ring sizes used in industrial seals.
4 min readUpdated July 2026
AS568 Standard O-Ring Sizes
AS568 is the Aerospace Standard for O-ring sizing. Each size has a dash number (e.g., -010, -016, -024) that uniquely identifies the inside diameter and cross-section.
Common Small Sizes
| Dash number | ID (mm) | Cross-section (mm) |
|---|---|---|
| -006 | 1.78 | 1.78 |
| -008 | 2.92 | 1.78 |
| -010 | 5.23 | 1.78 |
| -012 | 7.52 | 1.78 |
| -014 | 9.80 | 1.78 |
| -016 | 12.09 | 1.78 |
| -018 | 14.38 | 1.78 |
Common Medium Sizes
| Dash number | ID (mm) | Cross-section (mm) |
|---|---|---|
| -110 | 7.65 | 2.62 |
| -112 | 9.93 | 2.62 |
| -114 | 12.22 | 2.62 |
| -116 | 14.50 | 2.62 |
| -118 | 17.17 | 2.62 |
| -120 | 20.47 | 2.62 |
| -122 | 23.75 | 2.62 |
| -124 | 27.05 | 2.62 |
Common Large Sizes
| Dash number | ID (mm) | Cross-section (mm) |
|---|---|---|
| -210 | 11.13 | 3.53 |
| -214 | 15.70 | 3.53 |
| -218 | 20.29 | 3.53 |
| -222 | 24.87 | 3.53 |
| -226 | 29.44 | 3.53 |
| -230 | 34.01 | 3.53 |
| -234 | 38.59 | 3.53 |
Material Selection Guide
| Material | Temp range (°C) | Best for |
|---|---|---|
| Nitrile (NBR) | -30 to 120 | Oils, fuels, water |
| FKM (Viton) | -20 to 200 | Chemicals, high temp, steam (intermittent) |
| EPDM | -50 to 150 | Steam, hot water, acids, brake fluid |
| Silicone | -60 to 200 | Food, medical, high temp |
| PTFE | -200 to 250 | Chemicals, extreme temps |
| FFKM (Kalrez) | -20 to 320 | Extreme chemical and temp resistance |
How CHI can help
Ask CHI about O-ring sizing and to recommend the correct material for your fluid and temperature. The CHI assistant can look up specific values, explain what each table entry means, and help you cross-reference between different standards and unit systems.