Concrete Calculator
Enter your values below and click Calculate for instant results.
ft
ft
in
Calculate cubic yards of concrete for slabs, walls, columns, and footings. Shows bag quantities for DIY projects.
Enter your values below and click Calculate for instant results.
Concrete is sold in two forms: ready-mix delivered by truck in cubic yards, and bagged dry mix in 60-pound or 80-pound bags available at hardware stores. Ready-mix is economical for large pours, typically ordered in minimum quantities of one cubic yard. Bagged mix works for smaller projects like setting fence posts, pouring small slabs, or filling columns.
Always order 10% more concrete than your calculated volume to account for spillage, uneven sub-base, and the practical reality that perfect shapes are rare in construction. Running short mid-pour and having to add later creates a visible cold joint that weakens the structure.
A 60-pound bag of Quikrete mixed with water yields approximately 0.45 cubic feet of concrete. An 80-pound bag yields about 0.60 cubic feet. One cubic yard (27 cubic feet) requires approximately 60 of the 60-pound bags, or about 45 of the 80-pound bags. For anything over 1 to 2 cubic yards, ordering ready-mix is significantly more cost effective and physically easier than mixing bags.
Concrete reaches 70% of its full strength after 7 days of proper curing and approximately 90% after 28 days. During the first 24 to 48 hours, keep the surface moist and protected from freezing temperatures. Avoid walking on fresh concrete for at least 24 hours and avoid driving on it for at least 7 days.