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 turns the dimensions of any slab, walkway or column into three practical measures: cubic yards (the unit most suppliers quote), the number of 80‑lb bags you’ll need, and total cubic feet for planning. Why it matters – Knowing cubic yards prevents over‑ordering, which saves money and reduces waste. Bag count tells you exactly how many bags to order, avoiding multiple trips. How to read – Cubic yards = total cubic feet ÷ 27. Bags = total cubic feet ÷ 0.6 (round up). The results update instantly as you change any input, so you can experiment with thickness or area before you buy. You can also copy the bag count into your purchase list or share the link with a contractor. The calculator works on desktop and mobile, so you can measure on‑site with a phone.
Pro tips
- Add 5‑10% extra for spillage and uneven subgrade.
- Round bag count up to the next whole bag; you can’t buy a fraction.
- Order bags in full pallets when possible to reduce shipping cost.
- Double‑check thickness; a common mistake is entering inches as feet.
Real-life examples
- Homeowner pouring a 12 × 12 ft patio 4 in thick.
- Contractor estimating concrete for a 30 ft driveway 6 in thick.
- DIYer building a 4 × 8 ft garden bench foundation 3 in thick.
Case study
Mike needed a 10 × 15 ft slab 5 in thick for his garage. Using the calculator he saw he required 2.3 cubic yards, about 135 bags. He ordered 140 bags, saved a delivery trip, and finished on schedule.