Estimate cement, sand and coarse aggregate using CFT or m³. Adjust the mix, factors and material allowances.
How to use this tool
Enter your values and calculate a result. Check the units and assumptions before using the estimate.
Construction volume
Input unit
Output units
Dry volume factor
Cement mix parts
Sand mix parts
Aggregate mix parts
Cement bag volume (CFT)
Cement bag mass (kg)
Cement allowance (%)
Sand allowance (%)
Coarse aggregate allowance (%)
Material estimates use editable template assumptions. Cement bags assume 50 kg and 1.25 CFT per bag by default; adjust both for your product. Allowances are applied independently to each material. Structural steel percentages are preliminary quantities, not reinforcement design. The source row is labelled PCC 1:4:8, but its actual mix cells contain 1:3:6. This calculator defaults to the actual formula inputs 1:3:6.
How to use this calculator
Enter the measured quantity, choose the input unit and select your preferred output units. Open the mix and allowance settings to adapt the estimate to your materials and project.
Formula and assumptions
The calculation uses the following editable defaults. They are estimating assumptions, not a universal construction standard.
Measured volume
Measured surface area
Dry volume factor
1:3:6
Layer thickness (inches)
1.54
Assumed cement bag mass
1.25 CFT
Allowance
50 kg
V = measured volume in CFT; area input = square feet; D = dry material volume in CFT. In mix fractions C, S and A mean cement, sand and aggregate parts.
The source label says 1:4:8, but its mix inputs and calculations use 1:3:6. This tool follows the actual inputs. Change the mix to 1:4:8 in settings if that is your required specification.
D = V × 1.54
Cement bags = D × C / (C + S + A) / 1.25
Sand (CFT) = D × S / (C + S + A)
Aggregate (CFT) = D × A / (C + S + A)
Worked example
The example uses 100 CFT or 100 square feet, as appropriate. Base quantities match the template method. Each allowance is applied to its own material.
Material
Base quantity
With allowance
Cement
12.32 bags
12.936 bags
Sand
46.2 cft
57.75 cft
Coarse aggregate
92.4 cft
106.26 cft
Frequently asked questions
Can I enter metric quantities?
Yes. The tool converts m³ to CFT or m² to square feet before applying the same material formula. Selecting metric outputs converts material volumes and coverage areas back to m³ and m².
Does this specify a structural design?
No. Mix ratios, layer thicknesses and steel percentages are editable estimating inputs. Follow approved drawings, product specifications and the local requirements for your project.
What does the rounded purchase quantity mean?
Brick, brick tile and cement bag purchasing quantities round up after their individual allowances. The unrounded base quantity is also shown so you can compare it with the source method.
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