Test sieve selection is easiest when the required aperture opening is known. Mesh number, millimetres and microns are related ways of describing particle-size separation, but mesh numbering can vary between standards. For purchasing or test-method compliance, use the specified aperture and applicable standard as the final reference.
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
ASTM E11-24 covers woven-wire test sieve cloth, test-sieve construction, frame sizes and inspection procedures, while ISO 3310-1:2016 specifies technical requirements and test methods for metal-wire-cloth test sieves. BIS lists IS 460 Part 1:2020 as the Indian specification for wire-cloth test sieves. Because designation systems and referenced methods can differ, laboratories should order by the aperture and standard stated in the applicable test method rather than relying on a generic mesh-number conversion.
Official references: ASTM E11-24, ISO 3310-1:2016 and BIS IS 460 Part 1:2020.
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.