Concrete Slab Cost Calculator
Yards, bags, rebar and total cost for a concrete slab.
Enter your values
ⓘ Live results
Results
- Concrete needed
- 3.26 cubic yards
- 80 lb bags (DIY option)
- 134
- Concrete cost
- $521.48
- Labour
- $720.00
- Total project
- $1,241.48
- Slab area
- 240 sq ft
Working
- 120 x 12 x 0.33 / 27 = 2.96 yd3, +10% = 3.26
Quick answer
Volume = length x width x thickness / 27 cubic yards. Add 10% for uneven subgrade, then price by the yard delivered or by the bag.
yd3 = L x W x (thickness/12) / 27
How to use the Concrete Slab Cost Calculator
- 1Measure the slab footprint and choose a thickness: 4 in for patios, 5 to 6 in for driveways and garages.
- 2Add 10% for subgrade variation - running short mid-pour is expensive.
- 3Compare bag cost to ready-mix; ready-mix usually wins above about 1 cubic yard.
Worked example
Using the values the calculator loads with:
Inputs
- Slab length20 ft
- Slab width12 ft
- Thickness4 in
- Delivered price per yard160 $
- Labour per sq ft3 $
Results
- Concrete needed3.26 cubic yards
- 80 lb bags (DIY option)134
- Concrete cost$521.48
- Labour$720.00
- Total project$1,241.48
- Slab area240 sq ft
- 20 x 12 x 0.33 / 27 = 2.96 yd3, +10% = 3.26
Frequently asked questions
How thick should a concrete slab be?
4 inches for foot traffic and sheds, 5 to 6 inches with rebar for vehicles, and thicker with an engineered design for heavy equipment.
Do I need rebar or mesh?
Mesh or fibre for a patio; #4 rebar at 18 inch centres for driveways and anything carrying vehicles.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.