A Bar Bending Schedule (BBS) is a detailed table listing every reinforcement bar in a structural element or whole structure — its bar mark, diameter, shape, cutting length, number of bars and total weight. It tells the site exactly how to cut and bend the steel and how much to order.
The key figure is the cutting length: the straight length of bar needed before bending. It is the clear span between supports, minus the concrete cover at each end, plus allowances for hooks (about 9 times the diameter each) and minus deductions at bends (2d per 90° bend, 1d per 45° bend), because steel shortens slightly along its centre-line when bent.
Each bar's weight comes from the d²/162 kg/m unit-weight rule multiplied by its cutting length and count. Summing across the schedule gives the total steel, usually grouped by diameter for ordering. A BBS turns a structural drawing into a precise cutting and procurement list, reducing waste and errors on site.