CalcConcrete Slab Calculator
Last updated: 2026-05-09
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| Slab length (m) (m) | Slab width (m) (m) | Slab thickness (m) (m) | Steel (kg/m²) (kg/m²) | |
|---|---|---|---|---|
| Caso 1 | 2.4 m | 1.6 m | 0.1 m | 5.0 kg/m² |
| Caso 2 | 4.2 m | 2.8 m | 0.14 m | 8.4 kg/m² |
| Caso 3 | 6.0 m | 4.0 m | 0.2 m | 12.0 kg/m² |
| Caso 4 | 9.0 m | 6.0 m | 0.3 m | 18.0 kg/m² |
| Caso 5 | 15.0 m | 10.0 m | 0.5 m | 30.0 kg/m² |
What is a Concrete Slab?
A concrete slab is a flat, horizontal structural element used as floors, ceilings, or foundations. Solid slabs are continuous reinforced concrete masses with no voids, ideal for high-load applications, water-resistant structures, and flat soffits. Slab thickness typically ranges from 150mm for residential to 500mm+ for industrial.
Volume and Steel Calculation
Area (m²) = Length (m) × Width (m)
Volume (m³) = Area × Thickness (m)
Steel (kg) = Area × Steel density (kg/m²)
Typical steel densities: light slabs 8-12 kg/m², heavy slabs 15-25 kg/m².
Worked Example
A slab 6m × 4m × 0.20m with 12 kg/m² steel:
- Area = 6 × 4 = 24 m²
- Volume = 24 × 0.20 = 4.8 m³
- Cement = 4.8 × 7 = 34 bags (50 kg)
- Steel = 24 × 12 = 288 kg
Common Mistakes
- Using insufficient slab thickness leading to excessive deflection
- Not placing distribution steel perpendicular to main reinforcement
- Omitting bar chairs to maintain correct concrete cover
- Pouring in hot weather without cooling measures (cracking risk)
Standards
Calculated per EN 1992-1-1. Minimum slab thickness per Eurocode: 150mm for residential, 200mm for commercial.
Frequently Asked Questions
Residential slabs: minimum 100mm, typically 150mm. Commercial slabs: 150-200mm. Industrial slabs with heavy loads: 200-500mm.
No, formwork is calculated separately. For flat slabs, formwork area equals the slab soffit area plus edge forms.
All structural slabs need reinforcement. Even ground-bearing slabs require anti-crack mesh (typically A142 or A193) to control shrinkage cracking.