Filter Mesh Count Conversion: Threads per cm vs per Inch

To convert threads per centimetre to threads per inch, multiply by 2.54. To convert threads per inch to threads per centimetre, divide by 2.54. This changes the unit used to describe the same fabric. It does not turn mesh count into a micron opening or establish filtration performance.

For buyers comparing INCEFILTER filter mesh quotations, the first question is what the number counts and over what length. A quotation that says only “100 mesh” leaves a preventable ambiguity.

The conversion, with worked examples

The conversion follows the exact length relationship of one inch to 2.54 centimetres. A longer reference length contains more threads at the same fabric density, so the count per inch is numerically higher.

These are unit-conversion examples, not INCEFILTER stock specifications. Preserve the original count and unit in your purchase records. A supplier’s commercial grade label may be rounded; ask for the stated count and tolerance instead of treating a rounded label as an exact measurement.

Why equal counts do not guarantee equal openings

Count describes how often the fabric structure repeats over a length. Opening describes the clear space between adjacent threads. Thread diameter also occupies part of that repeat distance.

Consider an ideal square grid with 100 threads/cm in each direction. Its repeat distance is 100 micrometres. In a simple geometric illustration, a 40-micrometre thread leaves a 60-micrometre gap, while a 55-micrometre thread leaves a 45-micrometre gap. Both grids have the same count.

This illustration is not a certificate of measured aperture. Actual fabric geometry, weave and tolerances require the relevant product specification. Do not apply a square-grid calculation to a different weave without checking its construction.

Resolve a conflicting quotation before comparing prices

If one document says “100/cm” and another says “100/inch,” these are not equivalent specifications. Send both descriptions to the supplier and ask which fabric is intended. If a shorthand such as “T” appears, request its definition in writing rather than assuming a unit.

For a rectangular weave, record warp and weft counts separately. Converting one direction does not establish the other. Likewise, matching count alone does not establish material compatibility, finished dimensions or suitability for a particular liquid.

A clearer line for your request for quotation

Use a specification with separate fields: material; weave; warp count and unit; weft count and unit; thread diameter; required opening and tolerance; roll or cut-part dimensions; quantity; and service conditions. Mark any unknown field as “supplier to confirm.” Do not fill it with an estimate simply to complete the form.

Once a grade has been agreed, use the filter mesh incoming inspection checklist to align receiving checks with the approved specification. For repeat orders, retain the approved grade reference and revision so that unit conversions do not create a new, unintended specification.

Send INCEFILTER your mesh specification for review, including the original drawing or quotation, count units, required opening and intended application. Ask for availability and suitability to be confirmed for the proposed grade.

Technical reference: NIST, SI Units — Length, for the exact inch-to-metric relationship. The worked examples above are illustrative calculations.