Concrete Porch Calculator
Estimate concrete volume, bags, surface area, form perimeter, placed weight and cost for one or more uniform rectangular porch slabs.
Default project preview
1.63 yd³
Concrete bags
74
Porch area
96 ft²
Base volume
1.48 yd³
Form perimeter
40 ft
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Porch length
Enter this project assumption in ft. The current imperial default is 12 ft.
Porch width
Enter this project assumption in ft. The current imperial default is 8 ft.
Slab thickness
Enter this project assumption in in. The current imperial default is 5 in.
Equal porch slabs
Enter this project assumption in a unitless value. The current imperial default is 1. Minimum: 1.
Extra allowance
Enter this project assumption in %. The current imperial default is 10 %. Minimum: 0. Maximum: 50.
Concrete yield per bag
Enter this project assumption in ft³. The current imperial default is 0.6 ft³.
Ready-mix price
Enter this project assumption in per yd³. The current imperial default is 165 per yd³. Minimum: 0.
Price per bag
Enter this project assumption in a unitless value. The current imperial default is 7. Minimum: 0.
How to read the outputs
Concrete bags
rounded full bags. Default preview: 74.
Porch area
all slabs. Default preview: 96 ft².
Base volume
before allowance. Default preview: 1.48 yd³.
Form perimeter
all outside edges. Default preview: 40 ft.
Placed weight
planning density. Default preview: 6,592 lb.
Cost comparison
ready-mix / bags. Default preview: $268.89 / $518.00.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Volume = porch length × width × thickness × quantity. The allowance is applied before ready-mix conversion and bag rounding.
FAQ
Concrete Porch Calculator questions
Does this include porch steps?+
No. Estimate steps separately with the concrete steps calculator.
What about thickened edges?+
Add edge beams or footings as separate concrete shapes.
Can a porch slab attach to the house?+
Connection and movement details depend on the structure, soils and climate and require project-specific design.