Test sieve selection should start with the required nominal aperture opening. Millimetres and micrometres are units of length used to state an aperture; a mesh number is a separate designation related to the number of openings per unit length and the wire geometry. It is therefore not a universal substitute for aperture size. For purchasing or test-method compliance, use the nominal aperture and applicable standard stated by the governing method.
Mesh, micron and aperture: what is the difference?
Aperture size is the clear opening through the sieve media. It may be stated in millimetres or micrometres. A micron, written as µm, is one thousandth of a millimetre. Mesh terminology is commonly used for woven-wire sieves, but a mesh number should not be converted blindly without checking the relevant standard.
Test Sieve Aperture & Micron Conversion Chart
The safest way to specify a test sieve is by its actual aperture opening together with the applicable standard. The values below are direct metric unit conversions only: 1 mm = 1000 micrometres (µm). They do not claim that mesh or sieve-number designations are interchangeable between ASTM, ISO, BIS or other systems.
| Aperture (mm) | Aperture (µm) |
|---|---|
| 4.75 | 4750 |
| 3.35 | 3350 |
| 2.80 | 2800 |
| 2.36 | 2360 |
| 2.00 | 2000 |
| 1.70 | 1700 |
| 1.40 | 1400 |
| 1.18 | 1180 |
| 1.00 | 1000 |
| 0.850 | 850 |
| 0.710 | 710 |
| 0.600 | 600 |
| 0.500 | 500 |
| 0.425 | 425 |
| 0.300 | 300 |
| 0.250 | 250 |
| 0.212 | 212 |
| 0.180 | 180 |
| 0.150 | 150 |
| 0.125 | 125 |
| 0.106 | 106 |
| 0.090 | 90 |
| 0.075 | 75 |
| 0.063 | 63 |
| 0.053 | 53 |
| 0.045 | 45 |
| 0.038 | 38 |
Why mesh numbers should not be converted blindly
Mesh and nominal aperture are not identical terms. For accurate particle-size analysis, use the sieve aperture specified in millimetres or microns by the laboratory test procedure. Also confirm woven wire versus perforated plate and a compatible frame diameter before ordering.
Labtek Enterprises supplies test sieves in Delhi and across India for soil, aggregates, cement, sand and powder testing. Review our test sieve buying guide when comparing options.
How to choose the correct sieve size
- Start with the aperture specified in the laboratory method.
- Confirm whether woven wire or perforated plate is required.
- Select the frame diameter that matches the sieve stack or shaker.
- Confirm the frame and mesh material for the sample and environment.
- Check the referenced standard before placing the order.
For a detailed product example, see our 8 Inch Brass Test Sieve. You can also return to our Test Sieves page for the full range and selection assistance.