Home › Free tools › Concrete Slab Calculator
Free calculatorNo signupShort answer: Cubic yards = length (ft) × width (ft) × thickness (in) ÷ 12 ÷ 27. A 10×10 slab 4 inches thick is 33.3 cubic feet, or 1.23 cubic yards. Add 10% waste for 1.36 yards. In 80 lb bags, which yield 0.60 cubic feet each, that is 62 bags, or 82 bags of the 60 lb size.
Runs in your browser. Estimates only: check local code and your supplier.
Cubic feet = length (ft) × width (ft) × thickness (in) ÷ 12
Cubic yards = cubic feet ÷ 27
Order = volume × (1 + waste)
Bags = order (cu ft) ÷ bag yield
Bag yields from the Quikrete Concrete Mix data sheet: 80 lb = 0.60 cu ft (45 bags per yard), 60 lb = 0.45 (60 per yard), 50 lb = 0.375, 40 lb = 0.30. Add 5–10% for uneven subgrade, form bowing and spillage.
10 × 10 slab, 4 in thick, 10% waste:
All 7 paid HandyStack tools, including quotes, materials, invoices, rates and decks, for one price ($123 if bought separately). Save jobs, brand your quotes and stop re-typing numbers.
4 inches is typical for patios, walkways and shed floors. Driveways and slabs that carry vehicles are usually 5 to 6 inches. Follow local code and your engineer for structural slabs.
Bags make sense for small pours. Past roughly 1 cubic yard (45 bags of 80 lb), many pros order ready-mix or use a mix-on-site trailer to avoid hand-mixing.
No. Calculate the gravel base separately. A 4-inch compacted gravel base under a 4-inch slab is common.