Concrete Mix Calculator

Why Contractors Lose Money Here

Concrete is mixed on site by the shovel and the bucket. A mix that is 10% rich wastes cement on every pour; a mix with extra water loses strength that no curing brings back. Knowing the exact quantities per batch keeps both in check.

Real Site Example

1 m³ of M20 (1:1.5:3), no wastage: dry volume 1.54 m³; cement 1.54 ÷ 5.5 = 0.28 m³ = 403 kg = 8.06 bags; sand 0.42 m³ (14.8 cft); aggregate 0.84 m³ (29.7 cft); water at w/c 0.5 = 202 litres.

Professional Best Practices

Batch with gauge boxes sized to one 50 kg bag, add water by measure, and cast cube samples for every pour. Use a design mix for M25 and above.

Engineering Checklist

• Nominal mixes are for M20 and below (IS 456); M25 and above need a design mix
• Batch by weight or with gauge boxes, not shovels
• Measure the water; keep to the w/c ratio for the exposure
• Allow for sand bulking when batching wet sand by volume
• Cast cubes and cure them as IS 516 requires

Government & Standards References

• IS 456:2000 — Clause 9 and Table 9 (nominal mix), Table 5 (minimum cement and maximum w/c by exposure)
• IS 10262:2019 — Concrete mix proportioning guidelines
• IS 383:2016 — Coarse and fine aggregate for concrete
• IS 516 — Methods of tests for strength of concrete

How Experienced Contractors Handle This

Sites with steady quality use a design mix, batch by weight, and track cement per cubic metre poured against the mix design so over-use is seen at once.