Concrete Aggregate Mix Calculator
Enter concrete volume and mix ratio (e.g. 1:2:4) to work out the weight of cement, sand and gravel (aggregate) and the number of cement bags — handy for on-site mixing and delivery estimates.
Input Data
Results
At a glance:Let cement, sand and gravel parts be c, s, g; total parts T = c+s+g. Volume with waste V = volume × (1 + waste%). Total concrete weight = V × density; each component weight = total weight × part ÷ T. Cement bags = cement weight ÷ 50 (rounded up). Sand loose volume = sand weight ÷ 1,500 kg/m³; gravel loose volume = gravel weight ÷ 1,450 kg/m³. This uses a volume-part approximation ignoring water and voids, for on-site reference.
Formula
V = volume × (1 + waste%)
Total weight = V × density
Cement weight = total weight × c/T
Sand weight = total weight × s/T, gravel weight = total weight × g/T
Bags = ⌈cement weight ÷ 50⌉
$$V = V_0(1+w)$$$$W_t = V\rho$$$$W_i = W_t\frac{x_i}{T}$$$$B = \left\lceil \frac{W_c}{50} \right\rceil$$How to Use
- Enter concrete volume (m³).
- Choose the mix ratio (1:2:4 is common).
- Confirm density and waste.
- The system outputs cement bags, sand volume, gravel volume and total weight.
Case Studies
Floor slab concrete
1 m³, 1:2:4, density 2,400, waste 5%.
Total weight 2,520 kg; cement 343 kg (7 bags), sand 0.57 m³, gravel 1.14 m³.
Foundation blinding
2 m³, 1:3:6, density 2,200, waste 5%.
Total weight 4,620 kg; cement about 9 bags, sand 1.54 m³, gravel 3.09 m³.
FAQ
What is the difference between 1:2:4 and 1:3:6?
The former has less sand and gravel, relatively more cement, and higher strength; the latter has more gravel and less cement, lower strength and cost, often used for blinding or non-structural work.
Why separate volume and weight?
Delivery is measured by weight (cement bags, tonnes) and loose volume (sand/gravel trucks), while design uses solid volume, so conversion is needed.
Related Tools
References
Content review: Calculatorism Construction Team. Results are for reference only; please refer to the relevant authorities for the official figures.