Tolerances for Metric O-Rings

Due to the fact that there are literally dozens of O-Ring standards globally, finding a single recognized standard for metric O-Rings is virtually impossible. After extensive research, High Performance Seals has adopted tolerances based on ISO 3601-1, Class B, Annex A.4. The table below illustrates a few examples of tolerances using this standard. Sizes not shown can be calculated using the following formula:

Tolerance = ± [(Inside Diameter^0.93 x 0.009) + 0.11]

CROSS SECTION TOLERANCES (mm)
0.00 to 2.25 +/- 0.08
2.26 to 3.15 +/- 0.09
3.16 to 4.50 +/- 0.10
4.51 to 6.30 +/- 0.13 
6.31 to 8.40 +/- 0.15