Concrete Volume Calculator

Calculate concrete volume needed for your project. See cubic yards, cubic meters, and number of bags needed.

This calculator multiplies Length x Width x Depth (converted from inches to feet) to get volume, then converts to cubic yards, cubic meters, and 60/80 lb bag counts. Length, Width, and Depth sit on equal footing in the Rectangle and Slab formulas: each one is a plain multiplicand in a three-way product, with no exponent or offset favoring one over the others, so none of the three structurally outweighs the rest of the calculation. Shape changes the underlying formula rather than just scaling it: Rectangle and Slab use the identical Length x Width x Depth formula (a slab is just a rectangular pour by another name in this tool), while Circle instead treats Width as the diameter, computes area as pi x radius squared, and ignores Length entirely -- so for a circular pour, only Width and Depth matter, and changing Length has no effect on volume at all. That structural difference means switching shape can move the calculated volume more than a typical single-dimension tweak of ten percent or so: for a 10 ft x 10 ft square footprint, a circular pour of the same width uses about 21.5% less concrete than a rectangular one, since a circle inscribed in a square only covers pi/4 of its area -- a margin that's close to what a ~10% change in Length, Width, or Depth alone produces, so a larger single-dimension change can still outweigh the shape swap. Bag counts round up to the nearest whole bag, so always buy a small overage for waste.