The opening size is the distance between two adjacent wrap or weft wires,measured in projected plane at the mid-position.
Opening size tolerance
| Opening | Tolerance | ||
| In. | mm | In. | mm |
| 1/16 to 1/8 ,incl | 1.6 to 3.2, incl | ±0.007 | ±0.18 |
| Over 1/8 to 3/16, incl | Over 3.2 to 4.8, incl | ±0.010 | ±0.25 |
| Over 3/16 to 1/4, incl | Over 4.8 to 6.4, incl | ±0.012 | ±0.30 |
| Over 1/4 to 3/8 , incl | Over 6.4 to 9.5, incl | ±0.015 | ±0.38 |
| Over 3/8 to 1/2, incl | Over 9.5 to 12.7, incl | ±0.017 | ±0.43 |
| Over 1/2 to 3/4, incl | Over 12.7 to 19.1 , incl | ±0.020 | ±0.51 |
| Over 3/4 to 1, incl | Over 19.1 to 25.4, incl | ±0.030 | ±0.76 |
| Over 1 to 1-1/2, incl | Over 25.4 to 38.1, incl | ±0.045 | ±1.14 |
| Over 1-1/2 to 3, incl | Over 38.1 to 76.2 , incl | ±0.075 | ±1.90 |
| Over 3 to 5 , incl | Over 76.2 to 127.0, incl | ±0.100 | ±2.54 |
| Over 5 to 7, incl | Over 127.0 to 177.8 , incl | ±0.125 | ±3.18 |
| Over 7 | Over 177.8 | ±0.188 | ±4.78 |
