Particle Size Conversion Table SigmaAldrich
Smaller sieve "mesh" sizes of 3 1/2 to 400 are designated by the number of openings per linear inch in the sieve. The following convention is used to characterize particle size by mesh designation: a "+" before the sieve mesh indicates the particles are retained by the sieve; a "" before the sieve mesh indicates the particles pass through the sieve; typically 90% or more of .