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Rebar Spacing / Quantity Calculator
Calculate total number of bars, total length, and steel weight for a slab per IS 456:2000 bar weight standards
Structural
📋IS 456:2000 — Annex B & IS 1786:2008 (HYSD bar weights)
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Estimation tool only. Results are indicative — not a substitute for professional engineering design or site-specific survey. Always verify with a qualified civil, structural, or MEP engineer before ordering materials or commencing construction.
Calculate
Results are estimates only. Verify with a qualified engineer before use.
Formula
Bars along length = floor(slab_width / spacing) + 1 Bars along width = floor(slab_length / spacing) + 1 Total bars = bars_L + bars_W (two-way slab) Total length (m) = bars_L × slab_length + bars_W × slab_width Unit weight (kg/m) = diameter² / 162 (IS standard formula) Total weight (kg) = total_length × unit_weight
LSlab length (m)
WSlab width (m)
sBar spacing (centre-to-centre) (mm)
dBar diameter (mm)
d²/162IS unit weight formula (kg/m)
Reference Standard
IS 456:2000 — Annex B & IS 1786:2008 (HYSD bar weights)
Practical Tips
- •Add 10% to the calculated weight for lap splices, bends, hooks, and cutting wastage before placing the order.
- •IS 456:2000 specifies maximum bar spacing as 3× effective depth or 300 mm for slabs — whichever is less.
- •Use TMT Fe-500D bars (ductile version) in seismic zones III, IV, and V for better earthquake performance.