Concrete Calculator

This concrete calculator tells you how much concrete you need for a slab, footing, or pad. We multiply length by width to get the area, multiply by the thickness (converted from inches to feet) to get cubic feet, then divide by 27 to get cubic yards — how ready-mix concrete is ordered.

For smaller jobs, we also estimate 60-lb bags (each yields about 0.45 cubic feet). The cost estimate assumes about $130 per cubic yard of delivered ready-mix; bag prices vary by brand.

Always order a little extra (5–10%) for spillage and uneven subgrade. For large pours, ready-mix delivery is usually cheaper and faster than mixing bags by hand.