Calculate cement bags, sand and aggregate required for any concrete grade (M10, M15, M20, M25 and more).
The concrete calculator helps builders, contractors, and DIY enthusiasts calculate exactly how much concrete, cement, sand, and aggregate they need for any construction project. Whether you are laying a foundation, building a driveway, constructing a slab, or pouring columns, knowing the right quantities in advance prevents costly over-ordering or frustrating under-ordering of materials.
Concrete is made by mixing cement, sand (fine aggregate), coarse aggregate, and water in specific ratios depending on the strength required. These ratios are defined by concrete mix grades — M10, M15, M20, M25, M30, and higher. The number represents the characteristic compressive strength in N/mm² (MPa) at 28 days.
In India, M20 grade concrete (1:1.5:3 ratio of cement:sand:aggregate) is the most commonly used for residential construction including slabs, beams, and columns. M15 is used for lightweight construction and M25+ for commercial and structural applications.
\text{Wet Volume} = L \times W \times D \quad;\quad \text{Dry Volume} = \text{Wet} \times 1.54
Inputs: Slab: 5 m × 4 m × 0.15 m thick · Grade: M20 (mix ratio 1 : 1.5 : 3)
The M stands for Mix and the number represents the compressive strength in N/mm² at 28 days. M15 (1:2:4 ratio) is used for plain cement concrete work like flooring and pathways. M20 (1:1.5:3) is the standard for reinforced concrete slabs, beams, and columns in residential buildings. M25 (1:1:2) and above are used for commercial structures, bridges, and high-load applications where greater strength is required.
For M20 grade concrete approximately 8 bags of 50 kg cement are needed per cubic metre of wet concrete (≈ 6.24 bags/m³ of dry mix). For M15 approximately 6.5 bags/m³ and for M25 approximately 10.5 bags/m³. Always add 5–10% extra for wastage on site.
The recommended water-cement ratio for M20 concrete is 0.55 — meaning 0.55 litres of water per kilogram of cement. Using too much water weakens the concrete significantly. For a 50 kg bag of cement the maximum water is 27.5 litres. In hot climates like India, slightly less water is used as the concrete tends to dry faster.
Yes — always add 5–10% to all calculated quantities to account for spillage, uneven surfaces, and site wastage. For large pours above 10 m³ add 5%. For small jobs and irregular shapes add 10%. It is always better to have slightly more material than to run short mid-pour as a cold joint in concrete significantly weakens the structure.
Brick & Mortar Calculator Sand & Aggregate Steel Rebar Calculator
EMI Calculator Mortgage Calculator SIP Calculator Compound Interest GST / VAT Calculator Salary Calculator Unit Converter Currency Converter Scientific Calculator Paint Calculator Tile Calculator Calorie / TDEE Body Fat Macro Calculator O-Ring Sizes Bolt & Nut Sizes Pipe Sizes Wire Gauge AWG Needle Gauge Chart IV Cannula Sizes Suture Sizes Catheter French Sizes Drug Dosage See all 90+ calculators ›