Slab, Base, Excavation and Rebar Project Calculator
Estimate excavation, compacted base, slab concrete and reinforcing bar length for a rectangular foundation slab.
Formula
Planning estimate. Check product specifications and local requirements before purchasing.
Worked example: Slab Foundation Project Calculator
Measurements in this example
| Length | 10 m |
|---|---|
| Width | 8 m |
| Slab thickness | 15 cm |
| Compacted base depth | 20 cm |
| Rebar grid spacing | 20 cm |
| Waste allowance | 7 % |
Calculated quantities
| Excavation volume | 28 m³ |
|---|---|
| Compacted base | 17.12 m³ |
| Concrete for post holes | 12.84 m³ |
| Length with allowance | 875.26 m |
What to check
This calculation uses: Length, Width, Slab thickness, Compacted base depth, Rebar grid spacing, Waste allowance. It returns: Excavation volume, Compacted base, Concrete for post holes, Length with allowance.
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.