Concrete Slab Calculator

Calculating Concrete for Your Project

Getting the right amount of concrete is critical. Too little means a second delivery and a cold joint that weakens the slab. Too much wastes money. This calculator handles rectangular slabs, circular slabs, and cylindrical columns.

For rectangular slabs: length times width times depth. For circular slabs: pi times radius squared times depth. Column calculations use the circular formula applied to diameter and height multiplied by column count. All results include 10% waste factor.

Ready-mix concrete costs 25-75 per cubic yard. For smaller projects pre-mixed bags work better: 60-lb bags yield 0.45 cu ft, 80-lb bags yield 0.60 cu ft. The calculator recommends rebar spacing based on thickness for structural integrity.