Calculate preliminary beam depth and width using Thumb Rules, ACI 318, and IS 456 — for Simply Supported, Cantilever, Continuous, T-Beam and L-Beam.
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| Code / Method | Span/Depth | Min Depth | Width | Remark |
|---|
| Description | Value |
|---|
| Beam Type | Depth (D) | Width (b) | ACI L/d | IS 456 L/d |
|---|---|---|---|---|
| Simply Supported | L/12–L/15 | D/2–D/3 | 16 | 10–15 |
| Cantilever | L/7–L/8 | D/2–D/3 | 8 | 7 |
| Continuous | L/15–L/18 | D/2–D/3 | 21 | 12–15 |
| T-Beam | L/12–L/15 | bf/4–bf/6 | 16 | 12–15 |
| L-Beam | L/12–L/15 | bf/4–bf/6 | 16 | 12–15 |
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Our Beam Size Calculator provides preliminary beam dimensions using three recognized methods: Thumb Rules (industry standard practice), ACI 318 (American Concrete Institute), and IS 456 (Indian Standard). Supports 5 beam types — Simply Supported, Cantilever, Continuous, T-Beam, and L-Beam.
Simply Supported: D = L/12 to L/15 | Cantilever: D = L/7 to L/8 | Continuous: D = L/15 to L/18 | T/L-Beam: D = L/12 to L/15, Web width = bf/4 to bf/6
For simply supported beams, depth = Span/12 to Span/15. For a 5m span, depth ≈ 330–420mm.
Minimum width is typically D/2 or 200mm, whichever is greater.
IS 456 generally allows shallower beams (higher L/d ratios) compared to ACI 318 for the same span.