Steel Grating Open Area Percentage Calculator
Calculate the open area percentage for any bar grating specification. Open area determines drainage capacity, ventilation flow, light transmission, and debris retention. Enter bearing bar and cross bar dimensions to get your result instantly.
Bearing Bars
Top face width = thickness T
Clear space = pitch − thickness
Cross Bars
Round rod diameter or square side
Formula
OpenArea% =
[(P_bb − T_bb) / P_bb]
× [(P_xb − d_xb) / P_xb]
× 100
P_bb = Bearing bar pitch (c/c)
T_bb = Bearing bar thickness
P_xb = Cross bar pitch (c/c)
d_xb = Cross bar diameter or side
Application Guide by Open Area
< 40% — Minimal Drainage
Structural floors, heavy vehicle areas. Not recommended for water-intensive environments.
40–55% — Standard Industrial
Most common range. Suitable for walkways, platforms, mezzanines. Handles moderate drainage.
55–70% — Good Drainage
Suitable for wet processing areas, trench covers, oil & gas decks.
> 70% — High Flow
Drainage grates, screens, filtration applications. Maximum water and air throughput.
Open Area Results
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open
Open Area Percentage
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Solid Area
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BB Open %
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Suitability Rating
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Bearing bar clear gap:
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Cross bar clear gap:
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