The basic relationship between wire spacing, wire diameter, and clear opening can be expressed by a simple algebraic relationship:

Wire spacing (also called mesh spacing) can be defined either as a measured distance expressed in inches, or as the number of opening per lineal inch expressed as a count. Beware! Countless errors have occurred due to confusion between
2 mesh (1/2" on centers) and 2" mesh (2" on centers).

View Illustration of Wire Spacing

Most industrial specifications are produced with round cross section wire. Whenever possible, refer to the wire diameter in decimals of an inch, rather than gauge. Confusion between ferrous and non ferrous gauge numbers and sheet steel numbers results in incorrect wire diameters being specified. Standard wire diameters used are as follows:

Weight is simply the weight per unit area. It is typically expressed as lbs per square foot or kilograms per square meter. Generic weights per square foot shown in this web site are for steel. Conversion factors for other typical alloys are:

Percent open area is the ratio of hole area to total screen area at a 90° angle of incidence to the plane of the material, expressed as a percentage. Material with 40% open area will have 40 square inches of opening for every 100 square inches of material. Percent open area helps in comparing various materials as to how readily a product, whether it be corn, air, or light, will pass through the screen.

Mesh to Diameter ratio MD is the mesh spacing (center to center) divided by the wire diameter. We find this a very useful relationship. The MD can be used to determine appropriate crimp styles, and percent open area.
Illustration below demonstrates how MD correlates to Percent Open Area (POA).

For square mesh material (same spacing in both directions) and using the same wire dimensions in both directions, the Percent Open Area is:

Aspect Ratio is a useful way to characterize materials that have non-square or slotted openings or repeat patterns. It is the ratio of the larger pattern repeat distance to the smaller pattern repeat distance.

Banker Wire does recognize the fact that the traditional use of open area is inadequate for many applications involving light transmittance, whether it be for solar shading, or ascertaining the relative transparency of a material viewed at oblique angles. We have developed optical testing procedures and can provide performance curves for all our products. We refer to this enhanced version of Percent Open Area as Apparent Percent Open (APO).

View Illustration of Apparent Percent Open