Formulas for Determining Percentage of Open Area

In each formula “D” = hole diameter and “C” = center spacing

ROUND HOLE STAGGERED
PATTERN (60°)

Dia ²
Center ²
x
90.5
=
Percentage of Open Area

round_hole_staggered

ROUND HOLE STRAIGHT
LINE PATTERN (90°)

Dia ²
Center ²
x
78.54
=
Percentage of Open Area

round_hole_straight

ROUND HOLE DIAGONAL
PATTERN (45°)

Dia ²
Center ²
x
78.54
=
Percentage of Open Area

round_hole_diagonal