📊 Cement, gravel and sand per m³ of concrete (by mix)
Approximate quantities per 1 m³ of concrete for common nominal mixes (dry-volume factor ~1.54; 25 kg cement bags):
| Mix / grade |
Cement |
Gravel |
Sand |
| 1:3:5 · lean / blinding | ~6 bags | ~0.86 m³ | ~0.51 m³ |
| 1:2:3 · slab / H20 | ~8 bags | ~0.77 m³ | ~0.51 m³ |
| 1:2:2.5 · structural / H25 | ~9 bags | ~0.70 m³ | ~0.56 m³ |
| 1:1.5:2.5 · high strength / H30 | ~10 bags | ~0.69 m³ | ~0.41 m³ |
📐 Formula
Concrete volume (m³) = area × thickness. Then, per m³: cement, sand and gravel = 1.54 × (its part ÷ total parts of the mix). Cement kg = cement m³ × 1440; bags = kg ÷ bag size.
❓ Frequently Asked Questions
How much cement, sand and gravel per m³ of concrete?
For a 1:2:3 slab mix (~H20/C16/20) you need roughly 7-8 bags of 25 kg cement, ~0.5 m³ of sand and ~0.8 m³ of gravel per m³ of concrete, plus about 180 L of water. Richer mixes (H25/H30) use more cement.
How do I calculate the concrete volume of a slab?
Volume (m³) = area (m²) × thickness (m). For a 20 m² slab at 10 cm: 20 × 0.10 = 2.0 m³. Add 5-10% for waste and uneven ground.
Does a slab need reinforcement?
A ground slab or radier usually carries a welded steel mesh for crack control; a structural slab needs rebar designed by an engineer. This calculator estimates the mesh weight, not a structural design. Note: screed (Estrich) is a non-structural levelling layer and is a different calculation.