Mesh is a measurement of particle size often used in determining the particle-size distribution of a granular material.

For example, a sample from a truckload of peanuts may be placed atop a mesh with 5 mm openings.

Equivalent mesh sizes from 5 μm to 25.4 mm also exist.

For example the series 80mm, 63, 40, 31.5, 20, 16, 14, 10, 8, 6.3, 4, 2.8, 2 mm is routinely available in many European countries or the series with the larger steps 63, 31.5, 16, 8, 4, 2, 1 mm, 500 μm, 250, 125, 63 μm is commonly used to grade aggregates in the construction industry.

Some users replace some of those indicated above with 45, 22.4, 12.5, 11.2 and 5.6 mm sieves, mostly because of historical usage of such sizes in their country or industry.