Concrete slab material planner
Estimate excavation volume, slab concrete, compacted sub-base quantity, simple edge formwork length and sheet coverage for a rectangular slab.
Scope and safety: The thicknesses are YOUR inputs, not structural recommendations. This does not design reinforcement, footing details, slab strength, soil bearing, drainage, compaction, delivery, or building-code compliance.
Measurements and product assumptions
Transparent worksheet
Measurements are geometrical. No pricing, labour or engineering specification is implied.
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Calculations stay in your browser. CSV and print exports happen locally.
How the materials are calculated
Every allowance is an editable input. The calculator uses only user-provided dimensions and rates, rather than assuming regional products or construction codes.
- Slab plan area = length × width.
- Excavation = area × (slab depth + compacted base thickness); assumes uniform level excavation and no over-dig.
- Concrete volume = area × slab thickness × (1 + concrete allowance).
- Sub-base compacted geometric volume = area × base thickness × (1 + base allowance).
- Edge formwork = 2 × (length + width); assumes four free edges.
- Sheet area = slab area × (1 + overlap allowance); rolls, seams, edge upstands and specification are not designed.
Important exclusions
Sub-base volume is a compacted geometric target, NOT automatically an order volume of loose aggregate; your supplier must advise density, shrinkage and delivery. Rebar, membranes, chairs, fittings and finishes need independent specification.
Professional check: Confirm the construction design, real product label, site measurements and requirements with qualified contractors or engineers where necessary. No third party has independently certified these assemblies.
See BuildQuivo methodology and the individual calculator library.