Concrete Slab Calculator

Formula

1. Convert inputs to metres if using ft/in
2. wet_volume_m³ = length × width × thickness
3. volume_cft = wet_volume_m³ × 35.3147
4. dry_volume_m³ = wet_volume_m³ × 1.54
5. cement_m³ = dry_volume × 1 / (1 + 1.5 + 3) [M20]
6. bags = cement_m³ ÷ (50/1440)
7. mid_cost = wet_volume × price_per_m³
8. cost_range = mid_cost × (1 ± 0.15)

Assumptions

• Choose Metric (m, mm) or Imperial (ft, in) — both are common on Indian sites.
• Slab is a simple rectangle (length × width × thickness).
• Cement bags assume an M20 nominal mix (1:1.5:3) with dry volume = wet × 1.54.
• Standard Indian bag size is 50 kg; cement bulk density ≈ 1440 kg/m³.
• Cost range is ±15% around (volume × ₹/m³).
• No extra wastage beyond the dry-volume factor — add more for complex pours if needed.