How to Use the Steel Flat Bar Weight Calculator
A steel flat bar has a simple rectangular cross section, used for stair railings, bracing, brackets, and connection plates. Because the shape is so simple, you don't need a special beam formula — just thickness, width, and length are enough to get an accurate weight.
The area is thickness × width, and multiplying by the standard steel density factor 3.4028 (from 490 lb/ft³) gives the unit weight in lb/ft. Multiply by total length for the total weight. For example, a 3/8 in × 2 in flat bar has an area of 0.75 in², giving about 2.55 lb/ft.
The same density factor applies to any steel with a uniform rectangular section, such as plate stock, so this calculator is useful for quickly estimating order weight. Actual stock can vary slightly in thickness due to mill tolerance, so measure your material directly when precise order quantities matter.
Frequently Asked Questions
Multiply thickness by width to get the cross-sectional area, then multiply by the steel density factor 3.4028 to get weight per foot. Multiply by length for total weight.
Yes, any shape with a simple rectangular cross section (flat bar, plate) uses the same density factor. Shapes with complex profiles like beams or angles need a different area formula.