Bar Grating Calculator

Bar Grating Calculator

We have supplied this tool to assist our customers in determining the right Bar Grating for their application. To use this calculator, select a Span AND select either a U-Load OR C-Load quantity. The calculator will then recommend the appropriate bar size of 19W4/19W2 bar grating based on your specified criteria.

For example, by selecting a span of 4’ 0” with a U-Load of 533, the recommended bar size would be
1-1/2” x 3/16” 19W4/19W2.

Step 1


Step 2

Safe Uniform Load(U-Load)¹ or Safe Concentrated Load(C-Load)²

Symbol Bar Size Lbs/Sq. Ft.* Sec. Mod.** Deflection***


* Approximate weight Lbs./Sq. Ft. Weight depends on panel width, cross bar selection, mill tolerance, and manufacturing tolerance.
** Recommended maximum span for 1/4’’ deflection under concentrated load at 300# at midspan on 6’ or less. 400# over 6’.
*** Deflection in inches.

¹ Uniform Concentrated Load Lb/Sq. Ft.
² Safe Concentrated Load Lb/Sq. Ft. of grating width, at mid-span.

1/4’’ is recommended as the maximum deflection consistent with pedestrian comfort but can be exceeded for other loading conditions at the discretion of the engineer.

When serrated grating is required, the depth of grating for a specific load will be 1/4″ greater than that shown in the results of this calculator. The carrying capacity of a piece of grating subjected to a concentrated load over only a portion of it’s width is determined by the stiffness of both the bearing bars and the cross bars, and therefor differs with the type of grating used. To determine the carrying capacity of gratings subject to such loading the manufacturer’s engineering department should be consulted.

Conversion Factors:

For gratings with other than 1-3/16’’ bearing or spacing or for different design stresses, proportionate conversion factors apply. For information on other types of grating consult the manufacturer.


This bar grating calculator is intended for informational purposes only for pedestrian traffic. It has been developed using load table information supplied by the National Association of Architectural Metal Manufacturers for steel welded bar grating type 19W4/19W2. This information is of a technical nature, and as such is intended only for evaluation by technically skilled persons, with any use thereof to be at their independent discretion and risk. Such information is reliable when evaluated in the proper manner by licensed engineering personnel.