Make a bar bending schedule (BBS) for an RCC beam or lintel. Enter the span, the supports, the beam size and the bars from your drawing, and the calculator gives the cutting length of every bar and stirrup, the number of stirrups, and the steel weight by diameter. Part of our BBS calculators.
How to use the beam BBS calculator
- Choose Beam or Lintel.
- For a beam, enter the centre-to-centre span and, for each end, whether it rests on a column or another beam and how wide that support is.
- Enter the beam size, the cover, the top and bottom bars and the stirrup size and spacing.
- Open Extra bars, closer stirrups, anchorage for extra top bars at supports, extra bottom bars, or closer stirrups near the supports.
- Enter the number of identical beams and any wastage, then download the schedule as CSV, print it or share a link.
Beam BBS Calculator
Bar bending schedule for an RCC beam or lintel: cutting lengths, stirrups and steel kg
Extra bars, closer stirrups, anchorage
Bar bending schedule
Steel by diameter
Checks
Educational BBS for quantity estimate. Bar sizes, numbers, cover, anchorage, laps and stirrup spacing must come from the structural drawing; this is not structural design or a detailing sign-off. Rules follow common Indian practice (IS 2502 hooks and bends) as used in the source sheets.
Formulas used
| Bar | Cutting length |
|---|---|
| Top and bottom main bars | Anchorage at support 1 + clear span + anchorage at support 2 − 2 × 2φ (two 90° bends) |
| Anchorage into a column | 50φ by default (development length; change it to suit your drawing) |
| Anchorage into a beam | (supporting beam width − cover) + (its depth − 2 × cover) |
| Extra top bar at a support | Anchorage + length into the span − 2φ |
| Stirrup | 2 × (a + b) + 2 × 10φ − 2 × 3φ − 3 × 2φ, where a = B − 2c − φ and b = D − 2c − φ |
| Number of stirrups | Clear span ÷ spacing, rounded up, + 1 (or end zones at closer spacing plus the middle) |
| Lintel bars | Lintel length − 2 × cover (straight) |
| Weight | φ² ÷ 162 kg per metre × total length |
φ is the bar diameter and c the clear cover, in mm. Bars longer than the 12 m stock length get one 50φ lap for each extra piece.
Worked example
A 200 × 300 mm beam, 3000 mm centre to centre, resting on a 400 mm column at one end and a 200 × 300 mm beam at the other, with 25 mm cover, 2 bars of 12 mm at the top, 2 of 16 mm at the bottom and 8 mm stirrups at 130 mm:
- Clear span = 3000 − 400/2 − 200/2 = 2700 mm.
- Top bars: 50 × 12 = 600 into the column; (200 − 25) + (300 − 50) = 425 into the beam; 600 + 2700 + 425 − 48 = 3677 mm.
- Bottom bars: 800 + 2700 + 425 − 64 = 3861 mm.
- Stirrups: a = 142, b = 242; 2 × 384 + 160 − 48 − 48 = 832 mm; 2700 ÷ 130 = 20.8, rounded up to 21, + 1 = 22 stirrups.
Total steel: about 26 kg for one beam. These are the same rules as the site BBS sheets these tools were built from, except that stirrups are counted over the clear span only.
Frequently asked questions
How is the cutting length of a beam stirrup calculated?
Take the stirrup's centreline sides, a = B − 2 × cover − φ and b = D − 2 × cover − φ. Cutting length = 2(a + b) + 2 × 10φ for the two 135° hooks − 2 × 3φ for the two 135° bends − 3 × 2φ for the three 90° bends. For a 200 × 300 mm beam with 25 mm cover and 8 mm stirrups this gives 832 mm.
How is the length of beam main bars calculated in a BBS?
Main bar length = anchorage into support 1 + clear span + anchorage into support 2, minus 2φ for each 90° bend. Where the beam sits on a column, the anchorage is often taken as the development length, about 50φ; where it sits on another beam, the bar runs across that beam and bends down its depth, less cover.
How many stirrups are needed in a beam?
Number of stirrups = clear span ÷ spacing, rounded up, plus one. Many drawings use closer spacing near the supports (often over about twice the beam depth) and wider spacing in the middle; the calculator can split the count that way.
What are extra top bars at a support?
At continuous supports the top of the beam is in tension, so drawings add extra top bars over the support that run a set distance into the span, often about a third of the clear span. Take the number, diameter and length from your structural drawing.
How is a lintel BBS different from a beam BBS?
A lintel is a short beam over a door or window, usually the wall thickness wide and about 150 mm deep. Its bars are straight (length minus cover at both ends) with stirrups along the full length, and it bears about 150 mm or more onto the wall at each side.
Does steel grade change the weight in a BBS?
No. Fe 415, Fe 500 and Fe 500D bars of the same diameter weigh the same, φ² ÷ 162 kg per metre. The grade changes strength and development length, not weight.
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Disclaimer: Online educational publication only. Not a substitute for structural design or detailing by a licensed engineer. Full disclaimer · contact@speakarch.com
Last updated: 8 November 2026