How to use it
- Enter length in feet
- Enter width in feet
- Enter thickness in inches and hit Calculate
What it does – The calculator converts the length, width, and thickness you enter into three useful measures: cubic feet, cubic yards, and the number of 80‑lb bags needed. Knowing the exact volume prevents over‑ordering or costly shortfalls. Why it matters – Concrete is sold by the bag; each bag yields about 0.6 cubic feet. A small mis‑estimate can add extra trips or leave a project unfinished. How to read the results – Cubic feet is the raw volume of your slab. Divide by 27 to see cubic yards, the standard delivery unit. The bag count shows how many 80‑lb bags to order; round up to the next whole bag. Accurate ordering saves money on material and reduces site cleanup. It also helps you schedule deliveries efficiently.
Pro tips
- Add 5‑10% extra for waste and spillage.
- Always round the bag count up to the next whole bag.
- Order bags in multiples that match the supplier’s delivery minimum.
- Double‑check thickness; a 0.5‑in error can change bag count noticeably.
Real-life examples
- Homeowner planning a 12 ft × 15 ft patio 4 in thick.
- Contractor estimating concrete for a 20 ft × 30 ft garage floor 6 in thick.
- DIYer needing concrete for a 8 ft × 10 ft driveway repair 3 in thick.
Case study
Mike entered 12 ft × 15 ft × 4 in and saw 4.4 cubic yards, 210 bags needed. He ordered 210 bags, saved a $150 over‑order, and finished his patio on schedule.