Concrete Volume & Mix Calculator
Calculate concrete volume, dry materials, cement bags, sand, aggregate, and water for slabs, footings, and columns.
Project Inputs
Live Estimation Summary
Material Quantities & BOQ Breakdown
| Item Material | Calculated Quantity | Standard Unit | Est. Unit Price | Subtotal (INR) |
|---|---|---|---|---|
| Cement (50 kg Bags) | 64 Bags | 50 kg Bag | ₹24,320 | |
| Fine Aggregate (Sand) | 116.8 cu ft | cu ft (cft) | ₹6,424.19 | |
| Coarse Aggregate (Gravel/Stone) | 233.6 cu ft | cu ft (cft) | ₹10,512.31 |
Mathematical Formula
Overview & Explanation
Calculates exact concrete volume and dry ingredient proportions (cement bags, sand cu ft, aggregate cu ft) for construction.
How It Works
- Multiplies geometric dimensions to obtain wet volume.
- Applies dry volume safety multiplier of 1.54 for compaction and void fills.
- Computes cement, sand, and aggregate according to standard mix grade ratios.
Practical Applications
- Slab casting
- Footing concrete estimation
- Building column & beam pouring
How the volume is calculated
Concrete is ordered by volume. For a slab or footing, volume = length × width × thickness, with all three in the same unit. For round columns, volume = π × radius² × height. Always add a wastage allowance, because spillage, uneven ground and formwork bulging always use extra.
A wastage allowance of 5 to 10 percent is usual for ready-mix; hand-mixed concrete on small jobs often needs closer to 10 percent.
Worked example
A slab 5 m long, 4 m wide and 0.125 m (125 mm) thick holds 5 × 4 × 0.125 = 2.5 m³. With 7 percent wastage, order about 2.7 m³. For an M20 nominal mix of 1 : 1.5 : 3, the dry volume is about 1.54 times the wet volume, so 2.7 m³ needs roughly 4.2 m³ of dry materials: about 0.76 m³ of cement (around 22 bags of 50 kg), 1.14 m³ of sand and 2.27 m³ of aggregate.
Before you order
Measure thickness in several places, because ground is rarely flat and a few extra millimetres over a large slab add up. Mix ratios, reinforcement and curing should follow the structural drawings or IS 456 guidance for anything load-bearing; this calculator estimates quantities, not structural design.
Worked Example: 10m x 5m Slab (150mm thick)
Calculate materials for M20 concrete.
Calculate Wet Volume
10 × 5 × 0.15
Calculate Dry Volume
7.5 × 1.54
Cement Bags (M20 1:1.5:3)
(1 / 5.5) × 11.55 × 1440 / 50
Frequently Asked Questions
What is the dry volume conversion factor for concrete?
How many kg is 1 bag of cement?
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