As is standard for the irrigation industry, nothing is standardized! Irrigation filters are no different. Some manufacturers use a Mesh number or size while others use a Micron size number. Selecting the best filter for your irrigation project is confusing enough without trying to figure out what the difference between mesh and micron is. 


Mesh size is the “mesh number” (a US standard of measure for filter screens) in reference to the size of the opening in the screen. Mesh number technically refers to the number of openings in a linear inch of the filter screen material. So a screen with 30 openings along a linear inch of material is considered a 30 mesh screen. As the mesh number increases, the size of openings decreases, thus the larger the mesh number, the finer the filtration.


Micron is a term of measurement used to describe the size of tiny particles. Thus in filter screens, micron size refers to the maximum size of a particle that will pass through the filter screen. To get an understanding of a micron sized particle - with good but average vision you can see objects as small as about a tenth of a millimeter. A micron is one-thousandth of a millimeter. So in essence, the smaller the micron number the finer the filtration.


In relationship to the size of particle that will pass through that opening, we must consider the strand size of the filter screen material. Type of material or wire size may differ making the opening between strands vary. This may cause slight variances in mesh to micron conversion for various types of materials and manufacturers. It is important to remember that mesh size is not a precise measurement of particle (micron) size. 


Noted below are some common particulates and their approximate micron size for comparison.

ParticulateBacteriaClayGiardiaBeach SandFine SandSiltPlant SporesViruses
Micron Size0.3 - 60
0.1 - 2
8 - 14
62.5 - 2000
125 - 250
2 - 50
3 - 100
0.005 - 0.3


Common Mesh to Micron Conversion Chart


US Mesh

Inches

Micron

Millimeters

30

0.0232

595

0.595

35

0.0197

500

0.500

40

0.0165

400

0.400

50

0.0117

297

0.297

60

0.0098

250

0.250

70

0.0083

210

0.210

80

0.0070 

177

0.177

100

0.0059

149

0.149

120

0.0049

125

0.125

140

0.0041

105

0.105

170

0.0035 

88

0.088

200

0.0029

75

0.075

230

0.0024

63

0.063

270

0.0021

53

0.053

325

0.0017

44

0.044

400

0.0015

37

0.037


For additional assistance in selecting a filter to match your irrigation needs see our Filter Buying Guide.