How to Calculate the Right Amount of Ready-Mix Concrete for Your Slab

https://thebuildersguide.focalledger.com/posts/how-to-calculate-the-right-amount-of-ready-mix-concrete-for-your-slab

To calculate the right amount of ready-mix concrete for your slab, measure the length, width, and depth in feet, then multiply them together to get cubic feet. For example, a 10x10 slab that's 4 inches deep (0.33 feet) is 33 cubic feet. Since ready-mix is sold by cubic yard, divide cubic feet by 27. For 33 cubic feet, you'll need 1.22 yards, so order at least 1.25 yards to account for waste—it's better to have a little extra than run short.