Deck Concrete Calculator

Measure deck slabs and paths with confidence now. Compare bag counts, weight, and budget quickly. Save time, reduce waste, and order materials right first.

Tip
Use waste for uneven bases, spillage, and form leakage.
Common slabs: 75–125 mm (3–5 in).
m
m
m
m
m
Use 0 for a full circle.
Use measured deck area from drawings.
%
Typical: 5–10%.
kg/m³
Normal concrete is often near 2400 kg/m³.
Bag yields vary by brand and slump.
m³
Use manufacturer yield for best accuracy.
per m³
For delivered concrete, use local supplier quotes.
Reset
Example data table
Deck type Dimensions Thickness Waste Estimated volume
Rectangular slab 4.5 m × 3.2 m 100 mm 8% 1.56 m³
Circle pad Radius 1.8 m 90 mm 6% 0.97 m³
Ring planter base Rₒ 2.0 m, Rᵢ 0.9 m 75 mm 10% 0.77 m³
Values are illustrative. Actual results depend on inputs and site conditions.
Formula used
Area
  • Rectangle: Area = Length × Width
  • Circle: Area = π × Radius²
  • Ring: Area = π × (Rₒ² − Rᵢ²)
  • Custom: Area = user provided
Concrete volume
  • Volume (raw): V = Area × Thickness
  • Waste: Vw = V × (1 + Waste%/100)
  • Weight: W = Vw × Density
  • Bags: Bags = ceil(Vw / bag_yield)
Bag yield is an approximation unless you enter manufacturer values.
How to use this calculator
  1. Choose your unit system and deck shape.
  2. Enter dimensions and slab thickness from your design.
  3. Set a waste allowance for spillage and uneven bases.
  4. Select a premix bag size, or override its yield.
  5. Optional: add a cost rate for a quick budget estimate.
  6. Press Calculate to show totals above the form.
  7. Use CSV or PDF to save your material list.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.