Concrete calculator
Length and width in feet, depth in inches (default 4). Cubic yards, then waste.
CopiedAbout this concrete calculator
Slab or footing dimensions in, volume in cubic yards (and bags if the page shows a bag size) out — a materials estimate before you order.
Volume = length × width × thickness with unit conversions to cubic yards (÷27 from cubic feet). Bag count divides volume by the selected bag yield.
Not a structural mix design, rebar schedule, or PSI spec. Waste, pump line, and site conditions usually add a contingency your supplier will discuss.
FAQ
How is volume calculated? Cubic yards = length × width × (depth inches / 12) / 27. A 10×10 slab at 4 inches is 10 × 10 × (4/12) / 27 ≈ 1.23 cu yd before waste.
Why inches for depth? Slabs are usually specced in inches. 4 inches is 0.333 feet.
What is waste? A percent added on top of the raw volume.