Slab foundation concrete calculator

Estimate outputs: Main slab volume, Additional edge volume, Total concrete volume. Adjust Length, Width, Slab thickness to match your project.

Inputs and units

Use the units shown beside each field. Replace the sample values with your measurements and the figures on the selected product packaging.

Parameter	Example input
Length	10 m
Width	8 m
Slab thickness	15 cm
Thickened edge width	30 cm
Total depth at edge	45 cm
Waste allowance	7 %

Formula and assumptions

Main slab volume
Length × Width × Slab thickness / 100

Additional edge volume
(Length × Width - max(0, Length - 2 × Thickened edge width / 100) × max(0, Width - 2 × Thickened edge width / 100)) × max(0, Total depth at edge - Slab thickness) / 100

Total concrete volume
(Main slab volume + Additional edge volume) × (1 + Waste allowance / 100)

ceil = round up; floor = round down; max = the greater value. Trigonometric angles are converted from degrees to radians.

Allowance is applied before rounding to whole packages. Whole units are rounded up; displayed decimals are rounded only for readability.

Geometry and material quantities do not determine load capacity or reinforcement design. Use dimensions specified in the project.

Worked example

Sample values are examples, not product specifications. Run the calculation again with your own measurements.

Result	Calculation
Main slab volume	12 m³
Additional edge volume	3.132 m³
Total concrete volume	16.1912 m³

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