Civil Engineering
Concrete Volume Calculator
Estimate concrete volume for slabs, footings, pads, and other rectangular placements.
Parameter sketch
Slab dimensions
Labels update with the current input values so the formula symbols stay tied to the geometry.
Result
4.89 yd3 (3.74 m3) recommended order quantity
Base volume
120
Waste factor
10%
Cubic feet
132
Cubic yards
4.89
Cubic meters
3.74
Step-by-step calculation
- Convert thickness to feet: 0.5.
- Compute base volume: 20 x 12 x 0.5 = 120.
- Apply 10% waste factor: 120 x 1.1 = 132.
What this means
Use this as a preliminary quantity estimate and confirm ordering increments with the ready-mix supplier.
Formula Used
Volume = length x width x thickness
Step-by-Step Example
A 20 ft by 12 ft slab with 6 in thickness and 10% waste needs about 4.89 cubic yards.
Engineering Notes
Check units, assumptions, boundary conditions, groundwater, drainage, and whether the simplified method is appropriate before using a result in any project decision.
FAQ
Should I include waste?
Yes. Small jobs commonly use 5% to 10%; irregular excavations may need more.
Does this replace supplier takeoff?
No. Confirm delivery increments and site access with your supplier.