Free calculatorsTwo-Way Slab Design Calculator
Multi-code two-way spanning RC slab design — SANS 10100, BS 8110 and Eurocode 2. A self-contained finite-difference Kirchhoff plate solver returns the full Mx / My bending-moment fields, colour moment contours, top & bottom flexural steel each way, a span/effective-depth deflection check and a printable step-by-step calc sheet.
Plate solver validated against the Timoshenko closed-form thin-plate solution; STATIX runs 221 verified benchmarks
Inputs
Panel
Design code
Panel geometry
m
m
mm
mm
Edge support conditions
Loads (characteristic)
kN/m²
kN/m²
Materials
MPa
MPa
Slab steel — bar & spacing
Slab panel plan
Bending moment Mx field
Bending moment My field
Deflected shape
Design result
—
—
enter geometry
| ULS load n | — |
| Mx span / support | — |
| My span / support | — |
| X bottom (span) | — |
| X top (support) | — |
| Y bottom (span) | — |
| Y top (support) | — |
| Max deflection w | — |
Section
Reinforcement plan — interactive click a strip to edit · drag body to move · drag ends to curtail · double-click to add
Layer:
Demand map As,req:
As,req demand map (mm²/m)
bottom strip
top strip
deficient in X
deficient in Y
cut A–A
cut B–B
Section cuts — scrub the plan
Bending moment along the active cut
Steel along the active cut — required vs provided
Design checks
Step-by-step calculation
Combined bending schedule — all panels
Every panel in the project, aggregated from the FINAL detailing — bottom bars each way plus top strips only over edges that actually hog (with distribution bars along those supports). Bars per strip = floor(strip width / spacing) + 1. Shape codes per SANS 282:2004 (20 straight, 37 L-bend, 35 U-bar, 38 crank) — pick per mark below; cutting lengths are nominal (anchorage/laps to the detailer). Use “Add panel” above to build the full schedule, then Download PDF (print → Save as PDF).
221
This isn't a toy calculator
It runs the same engine as STATIX — a full structural suite validated against 221 closed-form and code benchmarks across analysis, design and connections — the full 3D modeller with native CBFEM is coming soon. Model the whole floor plate, not just one panel.