How to use it
- Enter the slab length in feet.
- Enter the width in feet.
- Enter the thickness in inches.
- Read the cubic yards, cubic feet and bag count results.
What it does – The calculator turns the dimensions of any slab, walkway or pad into three practical units: cubic yards (the standard ordering metric), cubic feet, and the number of 80‑lb bags needed. Why it matters – Ordering too little leaves you scrambling for more mix; ordering too much wastes money and space. Knowing the exact yardage lets contractors price jobs accurately and homeowners avoid surprise trips to the hardware store. How to read the results – Cubic yards = total cubic feet ÷ 27. Bags = cubic feet ÷ 0.6 (rounded up). The cubic‑feet figure shows the raw volume, while the yardage is what suppliers quote. Use the numbers to compare bids or plan material deliveries. If your project has a slight slope, measure the high and low points and use the average thickness for the most accurate estimate. The tool works on any device, so you can calculate on site or from the office.
Pro tips
- Add 5‑10% extra for waste and spillage.
- Round up the bag count to the next whole bag.
- Order a little more than the yardage to cover mix density variations.
- Double‑check measurements; a 1‑inch error can change bag count by several units.
Real-life examples
- A homeowner plans a 12 ft × 8 ft patio 4 in thick and needs to know how many bags to buy.
- A contractor quotes a driveway 20 ft × 30 ft at 6 in depth and wants the exact cubic yards for the bid.
- A DIYer wants to compare two suppliers for a 10 ft × 10 ft walkway 3 in thick.
Case study
Mike measured his 10 ft × 12 ft patio at 4 in thick, entered the numbers, and saw he needed 1.2 cubic yards, about 56 bags. He ordered 60 bags, avoided a second delivery, and finished on schedule.