Estimating
How Much Sand and Aggregate for a 1000 Sq Ft Slab? A Simple Guide
A back-of-the-envelope method to estimate your concrete materials — useful for budgeting before your engineer finalises the mix design.
One of the most common questions before a pour is "how much material do I need?" Here is a clear way to estimate it for a typical RCC slab, plus the method so you can redo it for your own dimensions. Treat these as planning figures — your structural engineer or RMC supplier will give the exact mix design.
Step 1 — Concrete volume
Take a slab of 1000 sq ft at 5 inches (0.125 m) thick:
- 1000 sq ft ≈ 92.9 sq m
- Volume = 92.9 × 0.125 ≈ 11.6 cubic metres (m³) of wet concrete
Step 2 — Dry volume
Dry materials compact when mixed with water, so we multiply by about 1.54:
11.6 × 1.54 ≈ 17.9 m³ of dry material to prepare.
Step 3 — Split by mix ratio
For a common M20 mix (1 : 1.5 : 3) — cement : sand : aggregate — the parts add up to 5.5:
| Material | Share | Approx. quantity |
|---|---|---|
| Cement | 1 / 5.5 | ~3.25 m³ → ~94 bags |
| M-Sand | 1.5 / 5.5 | ~4.9 m³ → ~8.5 tonnes |
| 20 mm aggregate | 3 / 5.5 | ~9.8 m³ → ~14.5 tonnes |
(To convert volume to weight we used rough bulk densities — about 1.75 t/m³ for M-Sand and 1.5 t/m³ for aggregate; cement at ~1440 kg/m³ ÷ 50 kg/bag.)
Adjusting for your job
- Different thickness? Scale linearly — a 6-inch slab needs about 20% more than a 5-inch one.
- Different mix? M25 and richer mixes use more cement and slightly less aggregate share.
- Add wastage: allow 3–5% extra for spillage and uneven surfaces.
A note on accuracy
These are estimates for budgeting and ordering, not a substitute for a designed mix. Always confirm the grade and ratio with your engineer, especially for structural elements. When you are ready, we can supply the M-Sand and aggregate by the tonne to match your estimate.
Need this delivered to your site?
Wilgro Infra supplies washed M-Sand, P-Sand and graded aggregates across Sarjapur, Hosur, Attibele and all over Bangalore — by the tonne or by the load, with sieve reports on request.