Enter your sizes
| Shape | Dia | a (m) | b (m) | Nos | Cutting length · weight | |
|---|---|---|---|---|---|---|
Assumptions (change if your office uses different constants)
Result
Common site practice (IS 2502 / SP 34 style). Check your drawing for lap lengths and development lengths — add them to a.
How it’s calculated
What a and b mean for each shape
| Shape | a | b | Cutting length |
|---|---|---|---|
| Straight | bar length | — | a |
| L-bar | long leg | short leg | a + b − 2d |
| U-bar | base | each leg | a + 2b − 4d |
| Bent-up (crank) | bar length | crank height | a + 2 × 0.42 b − 4 × 1d |
| Stirrup | member width | member depth | 2(A + B) + 2 hooks − 3 × 2d − 2 × 3d, with A, B = size − 2 × cover |
Questions
What is a bar bending schedule (BBS)?
A table of every bar in a member — its shape, diameter, number, cutting length and weight — used to cut and bend steel on site and to work out the total steel quantity.
How is the cutting length of a stirrup calculated?
Cutting length = 2 × (A + B) + 2 × hook length − bend deductions, where A and B are the member width and depth minus twice the cover. A rectangular stirrup has three 90° bends (2d each) and two 135° hooks (3d each); hook length is 10d (minimum 75 mm).
What are bend deductions?
When a bar is bent, its outer side stretches, so the measured length is more than the steel needed. Deduct 1d for a 45° bend, 2d for 90° and 3d for 135° (d = bar diameter).
How is the cutting length of a bent-up (crank) bar found?
Each crank adds 0.42 × crank height (for a 45° crank). For a bar with two cranks: length + 2 × 0.42 × h − 4 × 1d for the four 45° bends.
How do I find the weight of steel from the BBS?
Weight = D² ÷ 162 × cutting length × number of bars, added up by diameter. The calculator does this for every row.
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