Concrete Calculator

Find out how many bags of concrete mix you need for a slab, pad, or walkway.

How the concrete estimate works

• Volume in cubic feet is length times width times thickness in feet (thickness in inches divided by 12).
• A waste allowance is added, since ground is rarely perfectly level and some mix is always lost.
• One cubic yard equals 27 cubic feet.
• Bag counts use the typical yield for each bag size, rounded up to whole bags.

Before you pour

Bag yields vary a little by brand, so check the label. For larger pours, ready-mix delivered by truck is often easier than mixing dozens of bags. Thicker slabs, driveways, and anything that carries vehicle weight need proper base prep and may need reinforcement, so follow local code and check with a professional.