How to use it
- Enter the length in feet.
- Enter the width in feet.
- Enter the thickness in inches.
- Read the cubic yards, cubic feet, and bag count results.
What this calculator does
You input the length, width, and thickness of the slab you plan to pour. The tool converts those dimensions to total cubic feet, then to cubic yards (1 yd³ = 27 ft³), and finally divides the cubic feet by 0.6 ft³ per 80‑lb bag to tell you how many bags to order.
Why the numbers matter
Knowing cubic yards helps you communicate with concrete suppliers, while the bag count lets you budget for ready‑mix alternatives.
How to read the results
- Cubic feet – raw volume of your project.
- Cubic yards – the unit most contractors quote.
- Bags – round up to the next whole bag because you can’t order a fraction.
Pro tips
- Add about 10% extra for waste and spillage.
- Always round the bag count up to the next whole bag.
- Order a little more than calculated to cover variations in mix density.
- Double‑check that thickness is entered in inches, not feet.
Real-life examples
- A homeowner planning a 12 ft × 8 ft patio with a 4‑inch slab.
- A contractor estimating concrete for a 20 ft × 30 ft driveway at 6 in thickness.
- A DIY gardener calculating the volume for a raised‑bed path using 80‑lb bags.
Case study
Sam entered his 10 ft × 15 ft patio dimensions and 5‑inch thickness; the calculator showed 2.8 yd³ and 13 bags. He ordered 14 bags, avoided a short‑fall, and completed the pour on schedule.