How to use it
- Enter length in feet.
- Enter width in feet.
- Enter thickness in inches.
- View cubic yards, cubic feet, and bag count instantly.
What it does – The calculator takes the slab dimensions you input (length, width, thickness) and instantly returns three values: total volume in cubic feet, the equivalent in cubic yards, and the number of standard 80‑lb bags required. Why it matters – Knowing the exact volume prevents over‑ordering, saves money, and ensures your mix won’t fall short mid‑pour. Reading the results – One cubic yard equals 27 cubic feet; the bag count is derived from the fact that each 80‑lb bag yields about 0.6 cubic feet. Round up the bag total to the nearest whole bag to cover minor waste. You can use the result to compare prices between ready‑mix deliveries and bagged mix, plan site storage, and communicate exact needs to contractors. If you work on a DIY project, the bag count tells you how many pallets to order, while the cubic‑yard figure helps you verify that your concrete truck will fit the job.
Pro tips
- Add 5‑10% extra volume for spillage and uneven subgrade.
- Round the bag total up to the next whole bag; you can’t buy a fraction of a bag.
- Order bags in full pallets when possible to reduce shipping costs.
- Double‑check thickness; a common mistake is entering inches as feet.
Real-life examples
- A homeowner pouring a 6‑ft‑by‑8‑ft patio 4‑in thick.
- A contractor estimating concrete for a 20‑ft‑by‑30‑ft warehouse floor 6‑in thick.
- A landscaper preparing a 10‑ft‑by‑12‑ft garden path 3‑in thick.
Case study
Mike needed a 5 × 10 ft slab 4 in thick for a shed. Using the calculator, he saw he required 2.2 cubic yards, which translated to 13 bags. He ordered 14 bags, avoided a costly short‑run, and completed the pour on schedule.