Concrete Calculator
Estimate concrete for a rectangular slab: cubic yards, 80 lb and 60 lb bag counts and an estimated cost. Free, instant, 100% in your browser.
Runs locally in your browser — no upload, no trackingTry: Length=12, Width=12, Thickness=4, Waste allowance=10 → 52.8 ft³, 1.96 yd³, 89 (≈88), 118 (≈117.3), $293
How to use
Enter the length and width in feet and the thickness in inches, then add a waste allowance (10% is the usual rule for slabs). Press Calculate to see cubic yards, the number of 80 lb and 60 lb bags, and a rough material cost. Everything runs locally in your browser.
A 4-inch slab is standard for patios and walkways; use 5–6 inches for driveways or anything that carries vehicles. One cubic yard equals 27 cubic feet.
FAQ
How much concrete do I need for a 10×10 slab at 4 inches?
A 10×10 ft slab at 4 inches thick is 100 sq ft × (4/12) ft = 33.3 ft³, or about 1.23 cubic yards before waste. Add 10% and plan for roughly 1.36 yd³, which is about 3–4 80 lb bags per 0.6 ft³ yield (so 23+ bags), or one short-load truck.