How to use it
- Enter the slab length in feet.
- Enter the width in feet.
- Enter the thickness in inches and the price per cubic yard.
- Read cubic yards, bags, cubic feet, and estimated cost.
What it does – The calculator turns your slab dimensions (length, width, thickness) and the local price per cubic yard into four key numbers: total cubic feet, cubic yards, number of 80‑lb bags, and an estimated material cost.
Why it matters – Knowing exact volume prevents over‑ordering, saves money, and ensures you order enough concrete to avoid project delays.
How to read the results – Cubic feet is the raw volume of your slab. Divide by 27 to get cubic yards, the unit most suppliers quote. Multiply cubic feet by 1 ÷ 0.6 to see how many 80‑lb bags you’ll need. The Estimated cost is simply cubic yards × your price per yard. Use these numbers to get accurate quotes from concrete trucks. You can also adjust the thickness or price to compare different design options before committing.
Pro tips
- Add 5‑10% extra volume for waste and spillage.
- Round up bag count to the next whole bag.
- Order concrete a day ahead to secure delivery slot.
- Double‑check thickness conversion from inches to feet.
Real-life examples
- A homeowner planning a 10×12‑ft patio slab.
- A contractor estimating material for a 24×30‑ft garage floor.
- A DIY renovator sizing an 8‑ft wide, 2‑in thick shed foundation.
Case study
John needed a 12×20‑ft slab 4 in thick. Using the calculator he saw he required 1.5 cubic yards, about 67 bags, and a $180 material cost, so he ordered exactly that amount, avoiding a $200 over‑order and keeping his project on schedule.