Porch slab volume and material cost
Concrete Porch Calculator
Answer first: Enter your porch dimensions. Get cubic yards, bag count, and material cost — then compare ready-mix vs bags for your porch pour.
12 × 8 ft porch, 4 in thick
1.19 yd³ — about 54 bags
With 10% waste. Small enough for bags, but ready-mix is often easier.
Installed porch cost
$6–$12 per sq ft
Material only: $1.50–$4/sq ft. Labor and forms add $4–$8/sq ft.
Concrete Porch Calculator
Enter porch dimensions. Get volume, bags, and cost.
Cubic yards
1.3
80 lb bags
59
Ready-mix cost
$359
Bag cost
$295
Interactive workflow
Run the numbers, then save or export the project
Porch concrete: bags or ready-mix?
The right choice depends on your porch size and your tolerance for mixing.
| Benchmark says | Replace with local input | Next check |
|---|---|---|
| Small porch under 1 yd³ | A 8×6 ft porch at 4 inches = 0.59 yd³ — about 27 bags of 80 lb concrete. | Bags work well for small porches. Rent a mixer to avoid fatigue. |
| Medium porch 1–2 yd³ | A 12×8 ft porch at 4 inches = 1.19 yd³. Borderline — compare bag cost vs ready-mix delivery fee. | Use the calculator to compare both options with your local prices. |
| Large porch 2+ yd³ | A 16×10 ft porch at 4 inches = 2.22 yd³ — ready-mix almost always wins on cost and labor. | Call a local plant. Confirm minimum load and delivery fee. |
Concrete porch pour checklist
What to confirm before pouring a concrete porch.
| Signal to check | What it means | Next step |
|---|---|---|
| Sub-base | Gravel base is compacted and at least 4 inches deep under the porch. | Poor sub-base is the #1 cause of cracked porches. Don't skip it. |
| Forms | Forms are set, level, and staked. Edges are square. | Use 2×4 or 2×6 lumber as forms. Check level carefully before pouring. |
| Rebar or mesh | Reinforcement is in place (especially for porches that connect to the house). | ½ inch rebar on 18-inch grid is standard for porches. Wire mesh works for small pours. |
| Slope | Porch has a slight slope away from the house (1/8 inch per foot). | Proper slope prevents water pooling against the foundation. |
Related concrete planning tools
Move from a single calculation into a purchase, proposal, or pour-day decision with connected calculators and checklists.
How much concrete do I need for a porch?
A 12×8 ft porch at 4 inches thick needs about 1.19 cubic yards (54 bags of 80 lb concrete) with 10% waste. Use the calculator above for your exact dimensions.
How much does a concrete porch cost?
Concrete porch material costs $1.50–$4 per square foot. With labor, forms, and finishing, installed concrete porch cost is typically $6–$12 per square foot — about $600–$1,500 for a 100 sq ft porch.
Should I use bags or ready-mix for a porch?
For porches under 1 cubic yard, bags can be practical. Above 1–2 yards, ready-mix delivery saves time and usually costs less per yard. Compare both with the calculator using your local prices.
How thick should a concrete porch be?
Most concrete porches are 4 inches thick. If the porch will support vehicle weight or connects to a garage, use 5–6 inches. Add rebar or wire mesh for porches attached to the foundation.
Do I need rebar for a concrete porch?
Yes for most porches. Use ½ inch rebar on an 18-inch grid, or 6×6 wire mesh for small decorative porches. Rebar is especially important where the porch meets the house foundation.
Planning disclaimer
Volume and cost estimates are for planning only. Actual concrete needed depends on site conditions, form accuracy, and pour technique. Get quotes from local contractors and suppliers.