Concrete Calculator
Pick the element — slab, footing, round column or wall — enter its dimensions in metric or imperial units and how many you need. The calculator gives the concrete volume in cubic metres, cubic feet and cubic yards with your wastage allowance, then estimates the number of 50 kg cement bags, sand and coarse aggregate for a 1:1.5:3, 1:2:4 or 1:3:6 nominal mix using the standard dry-volume factor of 1.54.
How to use the Concrete Calculator
- Choose the element type and units.
- Enter the dimensions and the number of identical elements.
- Set a wastage allowance (5–10% is typical).
- Pick the nominal mix ratio.
- Press Estimate concrete to see volume and materials.
Features
- Slab, footing, round column and wall shapes
- Volume in m³, ft³ and yd³ with wastage
- Cement bags (50 kg), sand and aggregate quantities
- Mixes 1:1.5:3, 1:2:4 and 1:3:6
- Metric and imperial dimensions
Benefits
- Order ready-mix or materials with fewer trips and less waste
- Compare the cost of different mixes before you build
- Quick check of a contractor's material estimate
Frequently asked questions
Why multiply by 1.54?
Dry cement, sand and aggregate shrink in volume once water is added and the voids fill, so about 1.54 m³ of dry materials is needed for 1 m³ of wet concrete.
How many cement bags are in 1 m³ of 1:2:4 concrete?
About 6.3 bags of 50 kg: 1.54 ÷ 7 parts × 1 part of cement ≈ 0.22 m³, divided by 0.0347 m³ per bag.
Which mix should I use?
As a rough guide, 1:1.5:3 (about M20) is used for slabs, beams and columns, 1:2:4 (about M15) for general work and footings, and 1:3:6 for mass concrete and blinding. Follow your structural engineer's specification.
Are the quantities exact?
No. They are estimates; moisture and bulking of sand, compaction and site practice all change real quantities. Add a sensible wastage allowance.
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