How to use it
- Enter the slab length and width in feet.
- Input the thickness in inches.
- Type the price per cubic yard you pay.
- Click calculate to see cubic yards, cost, bags, and cubic feet.
The Slab Cost Estimator Calculator tells you exactly how much concrete you need and what it will cost — before you order. Enter your slab's length, width, and thickness, plus the price per cubic yard, and you instantly get four key numbers: cubic yards, estimated cost, number of 80-lb bags, and total cubic feet.
Why does this matter? Ordering too little concrete delays your pour and costs extra for a short-load fee. Ordering too much wastes money on material you don't need. This calculator removes the guesswork, so you can budget accurately and talk to your supplier with confidence.
Reading the results is simple: cubic yards is what you order from a ready-mix truck, bags is what you'd buy for a DIY mix (each 80-lb bag yields 0.6 cubic feet), and cost is the total based on your entered price. Use it for patios, footings, shed slabs, or any concrete project.
Pro tips
- Add 10% waste to your final cubic yards to cover spillage, uneven subgrade, and over-excavation.
- Round up when ordering bags — a partial bag is useless, so buy a full bag extra if you're close.
- For ready-mix, order the next full cubic yard to avoid short-load fees on small pours.
- Double-check your thickness in inches — many people measure the form height but forget the gravel base.
Real-life examples
- Planning a 10x12 concrete shed pad and need to budget the exact ready-mix order.
- Estimating how many 80-lb bags to buy for a 4-inch-thick patio slab.
- Comparing the cost of a 6-inch vs. 8-inch thick garage slab before pouring.
Case study
Mark, a DIY homeowner, planned a 12x16 slab for his garden shed. He guessed he needed 3 yards and 60 bags. Using the calculator, he entered 12, 16, 4, and $110/yard — it showed 2.37 cubic yards, $260.70, and 128 bags. He ordered 2.5 yards, saved $55, and had no leftover concrete.