← Back to Bead BoardSteel flat bar weight calculator
Flat bar at 0.2836 lb/in³. Width times thickness times length times density. A 2" × 1/4" flat bar is 1.70 lb/ft. A 4" × 1/2" is 6.81 lb/ft. Enter your dimensions, get the weight. The industry shortcut is 3.4032 × width × thickness for lb/ft.
Quick answer
Calculate A36 steel flat bar weight by width, thickness, and length.
Weights are calculated from published densities and standard section geometry. Real plate and bar stock runs ±2–3% from spec.
Steel flat bar weight per foot
Formula: width × thickness × 12 × 0.2836 lb/in³, or the shortcut 3.4032 × W × T. Standard stock lengths are 20 feet. Real bar varies ±2–3% from these numbers due to mill rolling tolerances per ASTM A6.
Questions welders ask about this one
How do you calculate flat bar weight per foot?
Multiply width times thickness times 3.4032. That constant is just 12 inches (one foot) times the density of mild steel (0.2836 lb/in³). Example: 2" × 1/4" flat bar = 2 × 0.25 × 3.4032 = 1.70 lb/ft.
What is the difference between flat bar and plate?
The math is the same — both are width × thickness × length × density. The difference is how they are made and sold. Flat bar is hot-rolled to shape in specific width/thickness combos and sold by the stick (20 foot lengths). Plate is rolled to a thickness and then sheared or burned to size from a larger sheet. If you are ordering a specific width under about 8 inches and a standard thickness, it is flat bar.
Is A36 the same weight as A529 or A572 flat bar?
Yes. A36, A529 Grade 50, and A572 Grade 50 are all 0.2836 lb/in³. The grades differ in yield strength and chemistry, not density. A529-50 and A572-50 are stronger (50 ksi yield vs 36 ksi for A36) but weigh the same per foot. Many mills now dual-certify A36/A529-50 from the same heat.
What are the most common flat bar sizes?
For welding shops: 1" × 1/8", 1" × 1/4", 1-1/2" × 1/4", 2" × 1/4", 2" × 3/8", 3" × 1/4", 3" × 3/8", 4" × 1/4", and 4" × 1/2". Widths from 1/2" to 12" are available, thicknesses from 1/8" to 1". Standard stock lengths are 20 feet.
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