Concrete Slab Details
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Enter your slab dimensions to see how much concrete you need.
Work out exactly how much concrete you need for a slab, pad, or pour. Enter your dimensions and get the volume in cubic yards or cubic meters, plus bagged concrete counts, with a built-in waste allowance.
Enter your slab dimensions to see how much concrete you need.
Length and width are measured in feet, thickness in inches. Dividing thickness by 12 converts it to feet; dividing the cubic-foot total by 27 converts to cubic yards, which is how ready-mix concrete is ordered. In metric mode the calculator works the same way with meters and centimeters, returning cubic meters.
As a rule of thumb, anything over about one cubic yard (roughly 45 of the 60 lb bags) is usually cheaper and far less work as a ready-mix delivery. For small repairs, post footings, and pads under ~1 yd³, bagged concrete makes sense — one 60 lb bag yields about 0.45 ft³ and one 80 lb bag about 0.6 ft³.
Subgrade is never perfectly level and some concrete is always lost to spillage and forms. Most contractors order 5–10% over the calculated volume; the calculator defaults to 10%. Coming up short mid-pour is far more expensive than a little extra.
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