Concrete Depot
Concrete Calculators & Tools
Dashboard-ready report tool
Concrete Patio Slab Calculator
Estimate concrete for a patio slab using length, width, and thickness. Get cubic yards, cubic feet, cubic meters, bag counts, cost, waste, a live 3D preview, and a printable Concrete Depot report.
Measurement inputs
Results update live as you type.
Used only in the report and dashboard.
Switches the starter units.
Most jobs use volume with waste.
5% simple, 10% normal, 15% complex.
Waste cannot be negative.
Optional. Leave blank if you do not want a cost estimate.
Cost cannot be negative.
Live 3D patio preview
The same SVG is saved in the report.
Length20 ft
Width12 ft
Thickness4 in
Order quantity with waste
Includes 10% waste. Base patio slab volume is 2.96 cu yd.
3.26 cu yd
Base concrete2.96 cu yd
Cubic feet80.00 cu ft
Cubic meters2.27 m³
Patio area240 sq ft
60 lb bags196 bags
80 lb bags147 bags
Estimated cost$488.89
Thickness4 in
This is an estimate. Always confirm the final concrete order with your supplier or contractor before placing an order.
Formula used
All measurements are converted to feet before the patio volume is calculated.
Volume = Length × Width × Thickness
Cubic yards = Cubic feet ÷ 27
With waste = Base volume × (1 + Waste ÷ 100)
Cubic yards = Cubic feet ÷ 27
With waste = Base volume × (1 + Waste ÷ 100)