Convert mesh size to microns — or microns to mesh — instantly. Filter the table by extrusion application and find the right filtration fineness for your process. For a complete guide to mesh size selection by application, see our Polymer Melt Filtration guide.
Used by process engineers across blown film, cast film, fiber spinning, recycling and compounding.
Enter a value, select the conversion direction, and choose your application to see the recommended filtration range highlighted in the table below.
Filter table by extrusion application:
| Mesh | Microns (μm) | Wire diameter (mm) | Typical applications | Notes |
|---|
Aperture sizes based on ASTM E11 / ISO 3310 wire mesh standards. Values are nominal; actual filtration performance depends on wire diameter, weave type, and polymer viscosity.
Mesh size selection is not arbitrary. The right filtration fineness depends on your polymer, contamination level, product quality requirements, and screen changer type. Here is the engineering rationale behind the most common configurations.
Post-consumer streams carry hard contaminants (paper, aluminium foil, sand) that would blind fine screens in minutes. Coarse filtration at 40–80 mesh removes gross particles. A secondary stage at 150–200 mesh polishes the melt. Gorillabelt handles contaminant loads up to 10% by weight continuously — no stops for screen change.
The workhorse range for most film extrusion. At 200 mesh (74 μm), gel particles and carbonised specs that cause pinholes and fish-eyes are captured before they reach the die. The AP Series operates continuously at any filtration level in this range — self-cleaning eliminates pressure spikes at screen saturation.
Fiber spinning demands sub-70 μm filtration to protect spinnerets from micro-contaminants that cause filament breaks. At 325–400 mesh, differential pressure rises fast: continuous self-cleaning is not optional, it is the only viable operating mode. The AP Series handles down to any filtration level required by these applications.
Engineering note: Mesh count alone does not define filtration fineness. Wire diameter, weave type (plain, twill, dutch weave), and open area percentage all affect the actual particle size retained. A 325-mesh plain weave and a 325-mesh dutch weave have significantly different filtration characteristics despite identical mesh counts. When specifying screen packs for critical applications, always confirm the micron rating with your supplier — not just the mesh number.
Mesh size is a US standard measurement representing the number of openings per linear inch in a wire mesh screen. A 200-mesh screen has 200 openings per inch — which translates to an aperture of approximately 74 microns (μm). The relationship is inverse: higher mesh numbers produce finer filtration and smaller apertures.
In plastic extrusion, the formula used for conversion is:
For the engineering principles behind mesh size selection
— including contaminant types, differential pressure, and
how filtration fineness affects product quality — see the
complete guide to polymer melt filtration.
Microns (μm) = ASTM E11 standard aperture
The converter above matches your value to the nearest official ASTM E11 standard mesh count, accounting for wire diameter.
This conversion is used daily by process engineers when selecting screen packs, specifying filtration equipment, or troubleshooting quality defects such as gels, fish-eyes, and black specks in film and fiber products.
Continuous screen changers reduce unplanned downtime by up to 90% compared to manual screen changes. But selecting the wrong filtration fineness is equally damaging: too coarse, and contaminants reach the die, causing quality rejects; too fine, and differential pressure rises rapidly, forcing frequent interventions even with clean virgin material.
According to industry data published by plastics processing trade groups, a single unplanned line stop costs between $200 and $500 per hour in lost output on a standard extrusion line running at 300–500 kg/h. At 15–45 minutes per manual screen change, with two to four changes per shift, the cumulative production loss exceeds 5–10% of annual output on high-volume lines.
Matching mesh size to the contamination profile of the incoming polymer is the first engineering decision. The converter and table on this page provide the baseline reference.
Two primary standards govern wire mesh specifications:
For practical purposes in extrusion, the two systems are interchangeable at the standard mesh counts listed in the table above. Discrepancies appear mainly at very fine mesh sizes (400+) where weave type begins to dominate filtration behaviour.
| Mesh | Microns (μm) |
| 40 | 635 μm |
| 60 | 420 μm |
| 80 | 177 μm |
| 100 | 149 μm |
| 150 | 105 μm |
| 200 | 74 μm |
| 250 | 63 μm |
| 325 | 44 μm |
| 400 | 37 μm |
Values shown are official ASTM E11 standard apertures (account for wire diameter).
Calculate Your Production Loss
Mesh size is the number of openings per linear inch in a wire screen. Microns (μm) measure the actual aperture size — the physical gap through which particles can pass. The two are inversely related: higher mesh = smaller aperture = finer filtration. To convert, divide 25,400 by the mesh number. For example, 200 mesh = 25,400 ÷ 200 = 127 μm (nominal, plain weave). Industry standards such as ASTM E11 and ISO 3310 define the exact wire diameter and aperture for each mesh count.
Blown film extrusion typically uses screen packs in the 100–200 mesh range (74–149 μm). For standard LDPE and LLDPE blown film, a 120–150 mesh screen removes gels and carbonised particles without excessive differential pressure buildup. High-clarity films and barrier applications often require 200–250 mesh (63–74 μm). When running post-consumer recyclate content, the coarser end of the range (80–120 mesh) is preferred to avoid premature screen saturation. A continuous self-cleaning screen changer such as the AP Series allows finer filtration without stopping the line for screen changes.
Change frequency depends on polymer cleanliness, throughput, and filtration fineness. On a virgin LDPE blown film line running at 300 kg/h with 150-mesh screens, intervals of 8–24 hours are common. With post-consumer recyclate, contamination levels of 3–8% by weight can saturate screens in 2–4 hours at equivalent fineness. Each manual screen change takes 15–45 minutes of downtime. Lines running 3 changes per 8-hour shift lose 45–135 minutes of production — equivalent to 5–10% of daily output. Continuous screen changers eliminate this downtime entirely by cleaning screens online without stopping melt flow.
200 mesh equals approximately 74 microns (μm) using the standard ASTM E11 plain weave aperture formula: 25,400 ÷ 200 = 127 μm nominal, adjusted to 74 μm actual aperture for standard wire diameter at this count. The 74 μm figure is the most widely cited reference in extrusion screen pack specifications. Use the converter above to calculate any other mesh-to-micron value, or consult the full table for the complete ASTM E11 series from 20 to 500 mesh.
325 mesh equals approximately 44 microns (μm). This is a fine filtration level used in fiber spinning (monofilament, multifilament), BOPP, and extrusion coating applications where sub-50 μm contaminants would cause filament breaks, optical defects, or coating failures. At 325 mesh, differential pressure across the screen pack rises significantly faster than at 200 mesh. Continuous self-cleaning filtration is strongly recommended: at this fineness, a manual screen change every 2–3 hours on a 500 kg/h line translates to over 300 hours of lost production per year.
Yes — directly and significantly. A clean screen pack contributes a baseline pressure drop (ΔP) across the filter, typically 20–80 bar depending on polymer viscosity, throughput, and mesh fineness. As the screen captures particles, ΔP rises progressively. When a screen pack is near saturation, ΔP can spike to 150–200 bar or more, causing melt pressure instability upstream that destabilises the bubble in blown film or creates thickness variation in cast film. Continuous screen changers maintain constant filtration area and constant ΔP — the AP Series holds melt pressure within ±2% during the self-cleaning cycle. This is the primary process engineering reason to upgrade from manual to continuous filtration.
Learn more about filtration equipment: Breaker plate vs screen changer — what’s the difference →
Enter your line throughput, stop frequency, and shift schedule. See your monthly lost production and the revenue left on the table — in under two minutes.
Mesh and micron tell you how fine your screen filters — but consistent filtration under pressure is what keeps an extrusion line stable. Cofit builds self-cleaning screen changers that hold that fineness without line stops.
Continuous screen changer (AP Series)
Self-cleaning double-cartridge filtration down to 3 μm.
Automatic belt screen changer (Gorillabelt)
For high-contamination recycling, up to 10% contamination.
Compare both systems
See the full screen changer range.
