Calculate concrete in cubic yards and bags for a slab.
A slab's volume is length times width times thickness converted to cubic yards. Adding an overrun allowance and converting to eighty-pound bags approximates the material needed. Ready-mix concrete is ordered in cubic yards, and an overrun buffer prevents running short mid-pour.
Concrete Volume
Cubic yards = length x width x thickness / 12 / 27
Cubic yards = length x width x thickness / 12 / 27 A slab's volume is length times width times thickness converted to cubic yards. Adding an overrun allowance and converting to eighty-pound bags approximates the material needed.
Ready-mix concrete is ordered in cubic yards, and an overrun buffer prevents running short mid-pour.
This calculator takes 4 inputs: Slab length, Slab width, Slab thickness, Overrun allowance. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.