Calculate how much concrete you need for slabs, footings, and columns. Results in cubic yards, cubic meters, and bags.
Slab: Multiply length x width x depth to get volume in cubic feet, then divide by 27 to convert to cubic yards. Cubic yards = (L x W x D) / 27
Round column: Calculate the area of the circle (pi x r^2), multiply by height, then divide by 27. Cubic yards = (pi x r^2 x H) / 27
Wall/footing: Multiply length x height x width and divide by 27. Same as a slab but oriented vertically.
Bag coverage: A standard 80 lb bag of concrete mix yields about 0.6 cubic feet. A 60 lb bag yields about 0.45 cubic feet.
Pro tip: Order 5-10% extra concrete to account for spillage, uneven ground, and form variations.