How to use it
- Enter length in feet.
- Enter width in feet.
- Enter thickness in inches.
- Read cubic feet, cubic yards, and bag count.
What it does – The calculator converts the length, width, and thickness you enter into three practical results: total cubic feet of concrete, the equivalent in cubic yards, and the number of 80‑lb bags required. Why it matters – Accurate volume saves money; ordering short forces a costly second delivery, ordering excess creates waste and heavier lifts. How to read the numbers – The cubic‑feet value is the raw volume. Divide that figure by 27 to see cubic yards, the unit most suppliers quote. Then divide cubic feet by 0.6 (the yield of one 80‑lb bag) and round up to the nearest whole bag. The output updates instantly, so you can tweak dimensions and see the impact before you call a contractor or place an order.
Pro tips
- Add a 10% waste allowance to cover spillage and over‑fill.
- Always round the bag count up; you can’t order a fraction of a bag.
- Confirm your supplier’s bag yield matches 0.6 cf per 80‑lb bag.
- Measure thickness from the finished surface, not the subgrade.
Real-life examples
- Homeowner planning a 12‑ft by 16‑ft patio 4‑in thick.
- Contractor estimating concrete for a 20‑ft driveway slab 6‑in thick.
- DIY gardener calculating footings for a raised garden bed 8‑in thick.
Case study
Mike needed a 10 × 12 ft patio 5 in thick. Using the calculator he saw the job required 2.2 cubic yards, which translated to 124 bags. He ordered 130 bags, avoided a second delivery, and completed the patio on schedule, saving both time and material costs.