How to use it
- Enter length, width, and thickness.
- Click Calculate.
- Read cubic yards, bags, and cubic feet results.
What it does – The calculator takes the length, width and slab thickness you enter and instantly converts them to three useful measures: total cubic feet, cubic yards, and the number of 80‑lb bags of concrete mix required.
Why it matters – Knowing cubic yards helps you order the right amount of ready‑mix, while bag count tells you how many retail bags to buy. Over‑ordering wastes money; under‑ordering delays projects.
How to read the results – Cubic feet is the raw volume of your pour. Divide by 27 to get cubic yards (the unit most suppliers use). Multiply cubic feet by 1 ÷ 0.6 (or simply divide by 0.6) to see how many 80‑lb bags you’ll need. Use the numbers to place an accurate order. The tool works on any device, so you can size a patio, driveway, or foundation on the spot.
Pro tips
- Add 5‑10% extra for waste.
- Round up bag count to the next whole bag.
- Order a little extra if you’re near a delivery cutoff time.
- Double‑check thickness conversion from inches to feet.
Real-life examples
- A homeowner estimating bags for a new 12 ft × 12 ft patio with a 4‑in. slab.
- A contractor sizing concrete for a 30 ft × 40 ft warehouse floor, 6 in. thick.
- A DIYer planning a garden walk that’s 8 ft wide and 2 in. deep.
Case study
Mike used the calculator for his 10 × 10 ft patio, 4 in. thick, got 56 bags, ordered 60, saved $200 vs over‑ordering.