Slab Span/Depth Ratio Checker
Deflection control by L/d limits for slabs and beams (IS 456 basic values).
This 'deemed-to-satisfy' check is how 95% of slabs skip explicit deflection math. A 4.2 m simple span at MF 1.3 needs d ≥ 162 mm — i.e. a 185–190 thick slab.
Formula
Slab Span/Depth Ratio Checker is a free span depth ratio for structural engineers, fabricators and site engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Slab Span/Depth Ratio Checker
Deflection control by L/d limits for slabs and beams (IS 456 basic values). The calculation implements L/d ≤ basic(7/20/26) × MF_tension-steel (IS 456 cl. 23.2.1). This 'deemed-to-satisfy' check is how 95% of slabs skip explicit deflection math. A 4.2 m simple span at MF 1.3 needs d ≥ 162 mm — i.e. a 185–190 thick slab.
How to use Slab Span/Depth Ratio Checker
- 1Enter Effective span in m.
- 2Enter Effective depth provided in mm.
- 3Enter Support type (1 cantilever (7) · 2 simply supported (20) · 3 continuous (26)).
- 4Enter Tension steel modification factor (From IS 456 Fig 4: ~1.2–1.6 for slabs).
- 5Read Actual L/d, Allowable L/d instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Slab Span/Depth Ratio Checker?
- ✓Implements the standard formula — L/d ≤ basic(7/20/26) × MF_tension-steel
- ✓Reference cited on-page: IS 456 cl. 23.2.1
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Built-in engineering verdict flags out-of-range results instantly
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Slab Span/Depth Ratio Checker use?+
It computes L/d ≤ basic(7/20/26) × MF_tension-steel, per IS 456 cl. 23.2.1. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
This 'deemed-to-satisfy' check is how 95% of slabs skip explicit deflection math. A 4.2 m simple span at MF 1.3 needs d ≥ 162 mm — i.e. a 185–190 thick slab.
Can I use this for real structural design?+
It implements the exact textbook/code formula cited below the result and is ideal for sizing, checking and learning. Final designs should be verified by a qualified engineer against the full code with all load cases.
Is the Slab Span/Depth Ratio Checker free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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