Tolerances of class A volumetric glassware
Class A tolerances of pipettes, volumetric flasks and burettes at 20 °C (class B is twice as wide), with the standard uncertainty for a rectangular distribution.
| Volumetric (transfer) pipette | 1 | 0.006 | 0.600 | 0.0035 |
|---|---|---|---|---|
| Volumetric (transfer) pipette | 2 | 0.006 | 0.300 | 0.0035 |
| Volumetric (transfer) pipette | 5 | 0.010 | 0.200 | 0.0058 |
| Volumetric (transfer) pipette | 10 | 0.020 | 0.200 | 0.0115 |
| Volumetric (transfer) pipette | 15 | 0.030 | 0.200 | 0.0173 |
| Volumetric (transfer) pipette | 20 | 0.030 | 0.150 | 0.0173 |
| Volumetric (transfer) pipette | 25 | 0.030 | 0.120 | 0.0173 |
| Volumetric (transfer) pipette | 50 | 0.050 | 0.100 | 0.0289 |
| Volumetric (transfer) pipette | 100 | 0.080 | 0.080 | 0.0462 |
| Volumetric flask | 10 | 0.020 | 0.200 | 0.0115 |
| Volumetric flask | 25 | 0.030 | 0.120 | 0.0173 |
| Volumetric flask | 50 | 0.050 | 0.100 | 0.0289 |
| Volumetric flask | 100 | 0.080 | 0.080 | 0.0462 |
| Volumetric flask | 250 | 0.120 | 0.048 | 0.0693 |
| Volumetric flask | 500 | 0.200 | 0.040 | 0.1155 |
| Volumetric flask | 1000 | 0.300 | 0.030 | 0.1732 |
| Burette | 10 | 0.020 | 0.200 | 0.0115 |
| Burette | 25 | 0.030 | 0.120 | 0.0173 |
| Burette | 50 | 0.050 | 0.100 | 0.0289 |
A tolerance is the largest systematic deviation an acceptable piece of glassware may have, not a random error; calibrated glassware can use its calibrated volume instead of the nominal one. ISO 648/1042/385 class A tolerances are the same for the common sizes (25 mL pipette ±0.03 mL, 50 mL burette ±0.05 mL) and differ slightly for a few others.