What is a bar bending schedule?
A bar bending schedule (BBS) lists every reinforcing bar in a member: its mark, shape code, diameter, number, bent dimensions, cutting length and weight. Fabricators cut and bend from it, and the site uses it to order and check steel.
How cutting length is calculated
BS 8666 gives a formula for each shape code. Dimensions A, B, C… are outside dimensions, so the formula deducts an allowance at each bend based on the minimum scheduling radius r and the bar diameter d. For example shape 21 (U-bar) is L = A + B + C − r − 2d. Weight per metre is d²/162 kg/m (steel density 7850 kg/m³).
Worked example
Shape 21, T16, A = 300, B = 5600, C = 300 mm. r = 32 mm for 16 mm bar. L = 300 + 5600 + 300 − 32 − 32 = 6136 mm → rounded up to 6150 mm. Mass = 1.580 kg/m × 6.15 m = 9.72 kg per bar; 4 bars = 38.9 kg. One 12 m stock bar gives 1 piece of 6150 mm, so 4 stock bars are needed.
How to use this tool
- Use the beam or column generator to fill the schedule quickly, or add rows by hand.
- For each row choose the shape code and diameter, then enter the dimensions shown in the shape help.
- Check the sketch and cutting length, then read the summary by diameter and the stock bars to order.
- Print the schedule or export it to Excel.
FAQ
Why is the cutting length less than A + B + C?
Dimensions are measured to the outside of the bar. When the bar bends, the outside length is longer than the centreline length, so a bend allowance is deducted.
How do I calculate rebar weight?
Weight (kg/m) = d² / 162, with d in mm. For example a 12 mm bar weighs 0.888 kg/m.
Which code should I use – BS 8666 or ACI?
Use the one in your project specification. Many Gulf and Pakistan projects schedule to BS 8666 shape codes while designing to ACI 318; this tool follows that practice.
What wastage should I add?
Typically 3–5 % for cutting waste and offcuts, depending on how well the bar lengths fit the 12 m stock bars.