| Primary value | 7.8 bags (≈ 390 kg cement per m³) |
| Applies to | Nominal mix M20 (1 : 1.5 : 3 cement-sand-aggregate) · Site-mixed or batched RCC concrete used in residential framing · Tender quantity calculation per cum of structural concrete |
| Exceptions | M15 — nominal mix 1:2:4 → 6.4 bags / m³ (≈ 320 kg) |
| M20 — nominal mix 1:1.5:3 → 7.8 bags / m³ (≈ 390 kg) | |
| M25 — design mix → ≈ 8.6 bags / m³ (≈ 430 kg) | |
| M30 — design mix → ≈ 9.2 bags / m³ (≈ 460 kg) | |
| PCC M10 (1:3:6) → ≈ 4.4 bags / m³ (≈ 220 kg) | |
| Per-bag mass (Indian) → 50 kg | |
| Measured as | Mass of cement consumed per cubic metre of compacted, finished concrete. Sand and aggregate volumes are adjusted for bulking, voids and dryness in detailed estimation. |
| Source | IS 456 — Table 5, Clause 9 ✓ Verified |
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Cement is 60–70% of the cost of concrete material — getting the bag count right per m³ is the single biggest lever in any tender estimation. The 7.8 bags/m³ for M20 is the BIS-derived theoretical figure; site practice adds 2–5% wastage to budget for spillage, contamination and partial bags.
Estimators apply 8 bags/m³ for M20 (rounded up + wastage) and 9 bags/m³ for M25. Site material managers check daily issue-vs-pour reconciliation to catch over-consumption early — a 10% slip on cement issued vs theoretical is the fastest sign of leakage or overordering.