Estimate cement, sand and coarse aggregate plus steel 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)
Steel volume percentage (%)
Steel density (lb per CFT)
Pounds per kilogram
Cement allowance (%)
Sand allowance (%)
Coarse aggregate allowance (%)
Reinforcement steel 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 template steel conversion uses 490 lb/CFT and 2.22 lb/kg. For an exact pound-to-kilogram conversion, set 2.20462262185 lb/kg.
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
1:2:4
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.
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)
Steel (kg) = V × 0.015 × 490 / 2.22
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
17.6 bags
18.48 bags
Sand
44 cft
55 cft
Coarse aggregate
88 cft
101.2 cft
Reinforcement steel
331.081081 kg
347.635135 kg
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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