How to use it
- Enter length in feet.
- Enter width in feet.
- Enter thickness in inches.
- Read cubic yards, bags, and cubic feet results.
What it does The calculator takes the three dimensions you enter—length (ft), width (ft) and thickness (in)—and converts them to a total volume. It shows that volume in cubic feet, then in cubic yards (the standard unit for concrete orders), and finally tells you how many 80‑lb bags you’ll need, using the industry‑accepted yield of 0.6 ft³ per bag.
Why it matters Knowing the exact yardage prevents over‑ordering (which wastes money) and under‑ordering (which delays projects). The bag count lets you order the right number of bags from the supplier.
How to read it
- Cubic feet – raw volume of your slab.
- Cubic yards – divide cubic feet by 27; this is what concrete trucks quote.
- Bags – cubic feet ÷ 0.6, rounded up to the nearest whole bag.
Pro tips
- Add 5‑10% extra for spillage and compaction.
- Always round bags up; you can’t buy a fraction of a bag.
- Order bags in multiples of 10 for better pricing.
- Double‑check thickness conversion from inches to feet before entering.
Real-life examples
- A homeowner pouring a 4 × 8 ft patio 4 in thick.
- A contractor estimating concrete for a 30 × 40 ft warehouse floor 6 in thick.
- A landscaper needing material for a 12 × 12 ft garden path 3 in thick.
Case study
Mike needed a 6‑in thick slab for his garage floor. Using the calculator, he entered 20 × 30 ft and got 37 cubic yards, 1,667 bags. He ordered 1,700 bags, avoiding a costly short‑fall and finishing on schedule.