Concrete Calculator
Calculate cubic yards, cubic feet, and bags of concrete needed for slabs, columns, and stairs.
60 lb = ~0.45 cu ft yield
Cubic Yards
1.23
ready-mix concrete
Ready-Mix vs. Bags
Under ~1 yard: bags are economical. Over 1 cubic yard: order ready-mix concrete from a batch plant. Ready-mix is typically priced per cubic yard ($125–$200 depending on region and mix design).
Free Concrete Project Tips
Mix ratios, curing times, and finishing techniques.
Frequently Asked Questions
How many bags of concrete do I need?
A 60 lb bag of concrete mix covers approximately 0.45 cubic feet. An 80 lb bag covers about 0.60 cubic feet. Divide your total cubic footage by the yield per bag to find how many bags you need. Always add 10% for waste.
How do I calculate cubic yards of concrete?
For a slab: cubic yards = (length × width × depth) / 27. Divide by 27 because there are 27 cubic feet in a cubic yard. Always measure in feet before dividing. Ready-mix concrete is ordered in cubic yards.
What is the standard thickness for a concrete slab?
A typical residential driveway is 4 inches thick. Sidewalks and patios are usually 3–4 inches. Structural slabs for garages or heavy loads should be 4–6 inches. Increase thickness for vehicle traffic or heavy loads.