Concrete Calculator

Multiply length × width × thickness to get cubic feet, divide by 27 for cubic yards, and size the bag count from there. An 80 lb bag of concrete is about 0.6 cubic feet, so the tool converts your volume into a bag count and adds a 10% spare. A 10×10 patio at 4 inches thick needs about 1.23 cubic yards — roughly 62 bags.