Grating Calculator

Standard welded steel bar grating sizes per ANSI/NAAMM MBG 531, common GCC/India metric bearing-bar sizes, a custom weight calculator, a load-span reference, and the offshore vs. onshore standards (DNV, API RP 2A-WSD, ABS, NORSOK, EN 1090, AS 1657) that actually govern grating selection. Free, no login required.

Calculator Sections

ANSI/NAAMM MBG 531 โ€” Welded Steel Bar Grating

Published designations and weights per the ANSI/NAAMM Metal Bar Grating Manual (MBG 531). Designation format: [bearing bar spacing in 16ths of an inch]-W[cross bar spacing in inches], e.g. 19-W4 = 1โ€‘3/16″ bearing bar spacing, welded, 4″ cross bar pitch.

DesignationBearing Bar (mm)Spacing (mm)Cross Bar Pitch (mm)Weight (kg/m²)Imperial ReferenceSource

Common GCC / India Metric Sizes

Bearing-bar and cross-bar sizes commonly stocked/manufactured for GCC and Indian industrial projects (per BS 4592-1 practice). Manufacturer designation codes vary by supplier โ€” the dimensions below are the controlling specification.

TypeBearing Bar h×t (mm)Spacing (mm)Cross BarPitch (mm)Weight (kg/m²)Source
Engineering Note: Rows marked NAAMM are the published standard weight โ€” use directly for design/procurement. Rows marked Calculated are computed from plain bar geometry (bearing + cross bar volume × density) and typically read 10–20% lower than a manufacturer's certified weight, because forge-welding/locking material and rolling tolerance are not captured by a pure geometric estimate. Always confirm against the manufacturer's certified weight for procurement, MTO, or structural design use. Standard reference: BS 4592-1:2006 (Industrial type flooring, walkways and stair treads โ€” Metal open bar gratings) and ANSI/NAAMM MBG 531.
โš™ Custom Panel Weight
๐Ÿ“Š Result
Weight per m²โ€”
Bearing bars contributionโ€”
Cross bars contributionโ€”
Bearing bars per panelโ€”
Total Panel Weightโ€”
Geometric estimate (bearing + cross bar volume × density). Typically 10–20% lower than a manufacturer's certified panel weight โ€” see note in the Standard Sizes tab. Not a substitute for a supplier's data sheet for procurement.

Uniform Load Capacity vs. Span

TypeSpan (m)Uniform Load (kg/m²)Deflection (mm)
Design Note: Bar grating is typically checked as a simply-supported beam strip under uniform or concentrated load, per ANSI/NAAMM MBG 531 or BS 4592-1 allowable-deflection criteria (commonly span/240 for industrial flooring, tighter for stair treads/walkways with vibration sensitivity). These figures are illustrative of load–span trend only โ€” take the governing allowable load from the current standard edition or the grating manufacturer's certified load table before specifying for a real structure.

Governing Standards โ€” Offshore vs. Onshore

Which standard governs your grating depends on whether the installation is offshore (marine/platform) or onshore (plant/refinery/building). These are the standards actually referenced on GCC oil & gas and industrial projects โ€” each has been checked against the standards body's own listing, not a vendor summary.

SectorStandardTitleScope / Applies To

Grating Construction Types

The dimensional tables above (NAAMM/metric) describe standard welded grating geometry. The type below determines the fabrication detail on top of that geometry โ€” pick the type that matches your project's safety and environment requirements, then use the Standard Sizes / Weight Calculator tabs for the dimensions.

Working an offshore platform, jacket, or FPSO deck? See the full Offshore Structural Engineering Tools โ€” wave force, pile capacity, fatigue (SCF/S-N), cathodic protection and jacket member design calculators.

ℹ Results are for reference only. Grating sizing, load-span, and weight figures must be independently verified against the current edition of ANSI/NAAMM MBG 531 (or BS 4592-1 for GCC/India metric jobs) and the specific offshore/onshore standard governing your project before use in design or procurement.