Concrete material calculator: cement bags, sand and aggregate
A slab, beam or footing is specified by wet concrete volume; buying is done by cement bags and cubic feet of sand and aggregate. Converting between them needs the dry-volume factor (1.54) and the mix ratio. This tool does that for the common nominal mixes.
- Wet concrete volume
- 7.08 m³ (250 cu ft)
- Sand
- 3.12 m³ (110 cu ft ≈ 5.0 t)
- Coarse aggregate
- 6.24 m³ (220 cu ft ≈ 9.4 t)
- Steel (TMT) estimate
- 566 kg (0.57 t)
- Water (approx.)
- 1,499 litres
Copy link to this calculation · JSON API · Estimates only; verify rates with the source below.
How it is calculated
Wet volume = L × W × thickness. Dry volume = wet × 1.54 (voids), plus wastage. Each ingredient = dry volume × its ratio part ÷ sum of parts (M20 = 1:1.5:3, sum 5.5). Cement in bags = volume × 1,440 kg/m³ ÷ 50. Sand ≈ 1,600 kg/m³, aggregate ≈ 1,500 kg/m³. Steel is a thumb-rule kg per m³ by element; the structural drawing governs. Water ≈ 25 litres per bag at w/c 0.5.
Worked example
A 30 × 20 ft, 5-inch M20 slab: 7.08 m³ wet, 11.45 m³ dry with 5% waste; cement 2.08 m³ = 60 bags, sand 3.12 m³ (110 cu ft), aggregate 6.25 m³ (221 cu ft), steel about 566 kg.
Frequently asked questions
How many cement bags for 1 m³ of M20 concrete?
About 8 bags (1.54 ÷ 5.5 × 1,440 ÷ 50 = 8.06), with 0.42 m³ sand and 0.84 m³ aggregate.
How much cement for a 1,000 sq ft slab?
At 5 inches thick in M20, roughly 100 bags of cement, 5.2 m³ sand and 10.4 m³ aggregate, with 900–1,000 kg of steel.
What is the dry volume factor and why 1.54?
Mixed concrete compacts: 1.54 m³ of loose dry ingredients produce about 1 m³ of wet concrete because of voids and water. Mortar uses 1.33.
Sources and what to verify: IS 456:2000 nominal mixes; standard estimating practice.
Estimates for planning only; not financial, legal or tax advice. Figures reflect common practice and published rates as of November 2026. Found an outdated rate? Email hello@zeorent.com.