How much cement, sand and aggregate is needed for 1 m³ of M20 concrete?

For M20 (1:1.5:3), 1 cubic metre of wet concrete needs about 8 bags (403 kg) of cement, 0.42 m³ of sand and 0.84 m³ of aggregate, based on a dry-volume factor of 1.54. Add 3 to 5 percent for wastage.

What is the dry volume factor for concrete?

Wet concrete volume is multiplied by about 1.54 to get the dry volume of materials, because the dry ingredients compact and lose volume when mixed with water.

What grade of concrete should I use?

M20 (1:1.5:3) is common for residential slabs, beams and columns. M15 suits PCC and footings, while M25 and above are used where higher strength is specified. Always follow your structural engineer's design.

Concrete Calculator (India)

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Tell us the volume of concrete and its grade, and we'll work out the cement bags, sand and aggregate — using the standard 1.54 dry-volume factor and the cement:sand:aggregate ratio for that grade. Add wastage and your local rates for a cost.

How it's calculated

Wet concrete shrinks as the dry ingredients fill the gaps, so the material (dry) volume is the wet volume × 1.54. That dry volume is split in the grade's cement:sand:aggregate ratio. The cement share is converted to 50 kg bags (one bag ≈ 0.0347 m³), and sand and aggregate are shown in cubic feet.

Dry volume = wet volume × 1.54 → split by grade ratio → cement ÷ 0.0347 = bags. Add 3–5% wastage.

Pouring a slab and need the steel too? Use the steel weight calculator. Costing the whole structure? See the construction cost calculator.

Frequently asked questions

How many cement bags for 1 m³ of M20?

About 8 bags (≈403 kg), with roughly 0.42 m³ sand and 0.84 m³ aggregate, before wastage.

Why multiply by 1.54?

Dry materials occupy more space than the finished wet concrete; 1.54 converts the wet volume you want into the dry quantity to buy.

Which grade for a house slab?

M20 is typical for residential slabs, beams and columns; M15 for PCC and footings. Follow your engineer's structural design.

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Frequently asked questions