Concrete Calculator - Kostenloser Online-Rechner

Concrete is the backbone of every Indian construction project - from rural village houses to multi-storey urban apartments, from rural panchayat roads to metropolitan bridges. Getting the quantity right matters because under-ordering halts work and over-ordering means wasted money plus disposal headaches (concrete sets within hours of mixing). This calculator gives you concrete volume in multiple units (cubic feet, cubic yards, cubic metres) and converts to 50 kg cement bags using standard Indian mix ratios. Used by homeowners building their own house, civil engineering students, contractors verifying material orders, and DIYers pouring driveways or footings.

Indian construction predominantly uses M-grade concrete designations: M15 (1:2:4 cement:sand:aggregate) for non-load-bearing items, M20 (1:1.5:3, the most common for residential slabs, beams and columns), M25 (1:1:2, for taller buildings or higher load), and M30+ for high-rise structures. Each grade has a specific cement content per cubic metre - M20 uses approximately 320kg (6.4 bags of 50kg) per m³, while M25 uses 360kg (7.2 bags). This calculator works with standard ratios; for design-mix concrete used in commercial projects, consult a structural engineer or use the exact mix design from the Bureau of Indian Standards (IS 456).

Volume calculation: simply length × width × thickness, with units consistent. The calculator handles unit conversion (inches to feet, mm to metres) automatically. For irregular shapes (L-shaped slabs, foundation footings with varying widths), break into rectangular sections, calculate each, and sum. Output is converted to cubic feet, cubic yards (1 yd³ = 27 ft³) and cubic metres (1 m³ ≈ 35.31 ft³).

Cement bag count for M20 grade (1:1.5:3): approximately 6.4 bags of 50kg cement per m³ of concrete. For M15: ~5 bags/m³. For M25: ~7.2 bags/m³. Plus sand (0.5 m³ per m³ of concrete for M20) and aggregate (0.7 m³). Water-cement ratio of 0.45-0.50 by weight gives workable concrete with adequate strength. Always order 5-10% extra for spillage, formwork settling, and slight over-pour at edges.

Wastage and quality: Real-world concrete pouring has 5-15% wastage from spillage, formwork seepage, and uneven base levels. Use 5% for ready-mix concrete (RMC, where mixing is precise), 10% for site-mix concrete (where workers measure approximately). Quality control essentials: slump test (50-100mm for slabs, 25-75mm for columns), 7-day and 28-day cube strength tests, proper vibration during pour, and curing for 14-28 days to develop full strength.