Slab Foundation with Thickened Edge Calculator
Calculate main slab, additional thickened edge and total concrete volume with an ordering allowance.
Formula
Planning estimate. Check product specifications and local requirements before purchasing.
Worked example: Slab Foundation Calculator
Measurements in this example
| Length | 10 m |
|---|---|
| Width | 8 m |
| Slab thickness | 15 cm |
| Thickened edge width | 30 cm |
| Total edge depth | 45 cm |
| Waste allowance | 7 % |
Calculated quantities
| Main slab volume | 12 m³ |
|---|---|
| Additional edge volume | 3.13 m³ |
| Total concrete volume | 16.19 m³ |
What to check
This calculation uses: Length, Width, Slab thickness, Thickened edge width, Total edge depth, Waste allowance. It returns: Main slab volume, Additional edge volume, Total concrete volume.
Use dimensions from the structural drawings and check excavation against them before concrete or steel is ordered.
The ordering figure excludes pump priming, severe overbreak and unrecorded level changes unless they are included in the inputs.
Foundation size, reinforcement, cover, joints and bearing conditions are structural decisions that require a qualified design.
Use the units beside each field. The values in the worked example are starting inputs; replace them with your measurements and the specifications of your material.
Compare alternatives
Open a tool, enter your measured dimensions, then save an estimate. Keep another version if you want to compare products or allowances.