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Concrete & Rebar Calculator with BBS
Pick your standard (IS / BS / ACI), auto‑load bar sizes & allowances, then build a Bar Bending Schedule and concrete take‑off with one click.
1) Choose Standard & Units
The calculator auto‑loads bar diameters, typical bend allowances and material properties for your chosen standard. You can edit allowances per project.
2) Material Library
3) Rebar Schedule & BBS
| # | Layer | Shape | Ø | Dims (clear) | Qty | Cut Length | Unit Wt | Total Wt |
|---|
Cut length uses current allowances for bends/hooks based on the selected standard. Hover a chip to see the formula; click to edit globally.
4) Concrete Take‑Off
Nominal mixes (e.g., 1:1.5:3) are provided for estimation. Design mixes should follow lab trials and project specifications.
5) Totals
What This Calculator Does & How It Works
Your one‑stop widget for steel rebar take‑offs (with BBS) and concrete quantities—aligned with IS / BS / ACI practices.
Quick Summary
This calculator helps you plan, estimate, and report rebar and concrete in minutes. Choose a detailing standard (IS/BS/ACI), add bars by shape, and instantly get a Bar Bending Schedule with total weights. Need concrete too? Select an element type and mix; the tool gives you volume and material breakdown (cement bags, sand, aggregate).
What It Calculates
- Bar Bending Schedule (BBS) — per row and totals: cut length, unit weight, total weight.
- Rebar shapes — Straight, L‑shape, U‑shape, Rectangular Stirrups/Ties, plus a mesh quick‑add.
- Concrete take‑off — Slabs, beams, columns, footings, or a custom volume. Includes wastage.
- Materials from mix ratio — Cement bags, Sand (m³), Aggregate (m³) for nominal mixes.
- Reports & exports — One‑click printable BBS and CSV export; save/load to your browser.
IS 2502/456/1786 BS 8666/4449 ACI 315/318 & ASTM/CRSI
How It Works (Step‑by‑Step)
1) Pick your standard & units
Choose IS, BS, or ACI (US). The calculator auto‑loads bar sizes, common grades, densities, and typical bend allowances for that region. Switch between Metric and US (in/ft/#bars).
2) Material library auto‑populates
Based on your selection, the tool fills in rebar grade options, concrete density, and bag size (e.g., 50 kg or 94 lb bags). You can still edit cover and allowances if your project demands.
3) Build your BBS
- Add rows for each bar layer/shape and enter clear dimensions. The tool applies bend/hook allowances to compute cut length.
- Unit weight uses the standard rebar formula
W = 0.006165 × d²(kg/m) for diameterdin mm. - For rectangular ties, clear dimensions are reduced by cover on each side before computing the perimeter.
- Use the quick‑add for mesh — provide panel size and spacing, and the tool creates two bar sets automatically.
4) Concrete take‑off in one view
Select an element type and nominal mix to get volume and constituent quantities. The results reflect your wastage % and the standard’s bag size.
5) Export, print, and share
Generate a clean printable BBS for approvals or site use, or export a CSV for Excel. You can also save/load your work locally.
Under the Hood: Formulas
| Topic | Formula | Notes |
|---|---|---|
| Unit weight | W = 0.006165 × d² (kg/m) | d in mm; density of steel ≈ 7850 kg/m³. |
| Straight bar | Cut = L | Clear length in meters. |
| L‑shape | Cut = A + B + k90·d | k90 is allowance in multiples of d. |
| U‑shape | Cut = A + B + C + (bends × k90·d) | Two 90° bends by default. |
| Stirrup/Tie | Cut = 2(Xclr + Yclr) + (bends × k135·d) + (hooks × kh·d) | Xclr, Yclr reduce for cover; hooks usually 135° ties. |
| Concrete volume | Slab: L×W×T · Beam: L×B×D · Column: H×X×Y · Footing: X×Y×D | Then apply wastage %. |
| Batching (dry vol.) | Dry = 1.54 × Volume | Estimator rule for nominal mixes. |
| Mix constituents | C : S : A parts from ratio | Cement bags from mass with 50 kg (or 94 lb) bag size. |
Default Values by Standard
IS 2502 / IS 456 / IS 1786
- Bars: 6, 8, 10, 12, 16, 20, 25, 28, 32, 36, 40 mm
- Grades: Fe415, Fe500, Fe500D, Fe550
- Allowances (editable): 90° = 2d, 135° = 3d, Hook = 10d
- Densities: Steel ≈ 7850 kg/m³, Concrete ≈ 2400 kg/m³
- Nominal mixes: M10 (1:3:6), M15 (1:2:4), M20* (1:1.5:3)
BS 8666 / BS 4449 / EN 1992
- Bars: 8, 10, 12, 16, 20, 25, 32, 40 mm
- Grades: B500A/B/C
- Allowances (editable): 90° = 2d, 135° = 3d, Hook = 10d
- Densities: Steel ≈ 7850 kg/m³, Concrete ≈ 2400 kg/m³
- Nominal mixes: GEN1, C20/25* (1:1.5:3), Design Mix
ACI 315 / ACI 318 / ASTM A615 (CRSI practice)
- # Bars: #3 to #11 (9.5 to 36 mm eqv.)
- Grades: 40, 60, 75 ksi
- Allowances (editable): 90° & 135° bends in kd; hooks often 12d for 90° (ties commonly 135°)
- Densities: Steel ≈ 490 lb/ft³ (7850 kg/m³), Concrete ≈ 150 lb/ft³ (2400 kg/m³)
- Nominal mixes: 3000 psi* (1:2.5:4.5), 4000 psi* (1:2:3)
*Nominal mixes and allowances shown are common estimating defaults. Always verify against your project specifications and local codes.
Assumptions & Limits
Allowances are provided as multiples of diameter (kd) and are editable. Project‑specific detailing (development/anchorage, seismic hooks, lap lengths) should be taken from the structural drawings and codes.
Nominal mix ratios are for preliminary estimates. Final quantities for procurement should be based on design mixes proven by lab trials and QA/QC requirements.
This tool focuses on bar shaping and concrete volume. It does not calculate splice design, bar development lengths, or code‑required minimum reinforcements. Refer to your design codes and drawings.
Pro Tips
- Use the mesh quick‑add for slabs — it creates orthogonal bar sets from panel size and spacing.
- Set cover early; it directly affects stirrup/tie cut lengths.
- Export the CSV and attach it to your IFT/IFC transmittals for traceability.
- Print the BBS and get it initialed by the site engineer before cutting to reduce waste.
FAQ
Yes. Click the allowance chips in the calculator (e.g., 90° = 2d) to set your own k values per project.
Yes. Switch units to US; the tool maps #3–#11 to their metric diameters internally.
They are common estimating mixes. For production, use design mixes conforming to your code (IS/EN/ACI) and project specifications.
