RCC Slab Concrete Calculator

RCC slab concrete quantity calculator with cement, sand and aggregate for 1:2:4 mix presets. Use the free RCC Slab Concrete Calculator below — enter your values and get instant results, right in your browser. Wet volume (cu ft) = length × width × thickness/12. Dry volume = wet × 1.52. Cement bags = dry(m³) × 1/mix-sum × 28.8; sand and aggregate split by their mix parts (e.g. 2/7 and 4/7 for 1:2:4).

How to use the RCC Slab Concrete Calculator

The slab pour is the biggest single material order on a house project, and a shortfall means a cold joint across your roof — a structural weakness you cannot fix later. This RCC slab concrete quantity calculator takes your slab length, width and thickness, applies the 1.52 dry-volume factor that accounts for voids in sand and aggregate, and splits the result across the standard 1:2:4 mix (or richer and leaner presets). You get wet concrete volume plus the cement bags, sand and crush needed, all in one screen.

  1. Enter the slab length and width in feet in their fields.
  2. Enter the slab thickness in inches (usually 4 to 6 inches for house slabs).
  3. Select the concrete mix — 1:2:4 is the standard for residential slabs.
  4. Click Calculate to see concrete volume, cement bags, sand and aggregate.
  5. Order about 5% extra aggregate to cover spillage at site.

Formula

Wet volume (cu ft) = length × width × thickness/12. Dry volume = wet × 1.52. Cement bags = dry(m³) × 1/mix-sum × 28.8; sand and aggregate split by their mix parts (e.g. 2/7 and 4/7 for 1:2:4).

Worked example

A 20 × 15 ft slab, 5 inches thick: wet volume = 125 cu ft. With 1:2:4 mix, dry volume = 190 cu ft (5.38 m³). Cement = 5.38 × 1/7 × 28.8 = 22.1 bags; sand = 54.3 cu ft; aggregate = 108.6 cu ft.

Frequently asked questions

At 5-inch thickness with 1:2:4 mix, roughly 74 bags of cement, 181 cu ft of sand and 362 cu ft of aggregate — use the calculator with your exact thickness.

Dry materials contain air voids, so you need about 1.52 times the wet concrete volume in dry cement, sand and aggregate.

1:2:4 is the standard residential RCC mix. Use 1:1.5:3 only where the engineer specifies richer concrete.

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