Concrete calculator

Metric Concrete Calculator

Concrete shape

SlabFootingPost hole

Slab length (m)Overall slab length.Slab width (m)Overall slab width.Slab thickness (mm)

Footing length (m)Footing width (m)Footing depth (m)

Hole diameter (mm)Hole depth (m)Number of holes

Waste percent (%)Allows for spill, uneven excavation, and ordering margin.Supply outputNo supplier claims are made.Bag yield (m3 per bag)Editable assumption from your bag label.Price per bag (optional)Shown only for bag estimates.

Estimate

Enter measurements and calculate to see the concrete estimate.

Formulas and assumptions

Slab volume = length x width x thickness in metres.
Footing volume = length x width x depth.
Post-hole volume = pi x radius squared x depth x hole count.
Waste-adjusted volume = base volume x (1 + waste percent / 100).
Bag estimates divide waste-adjusted m3 by editable bag yield and round up to whole bags.

Planning estimate only. Not engineering, structural, legal, installation, or supplier advice. Check measurements, site conditions, and product labels before buying or building. This calculator estimates concrete volume only.

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Metric-first material estimates for practical home projects. No accounts, tracking, supplier price feeds, or hidden assumptions.

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Check measurements, product labels, and site conditions before buying or building.