Construction

Concrete Calculator

Calculate cubic yards, cubic feet, and concrete bag counts for slabs, footings, and columns.

Reviewed & Maintained by

Aadil Malik — Software Engineer

1 min read · 30 words

What is a Concrete Calculator?

A concrete calculator computes the required volume in cubic yards, cubic meters, and pre-mixed bag quantities for rectangular slabs, footings, steps, and cylindrical columns.

Frequently Asked Questions

Length (ft) * Width (ft) * [Thickness (in) / 12] / 27 = Cubic Yards of concrete.

It takes approximately 60 bags of 60-lb concrete, or 45 bags of 80-lb concrete, to yield one cubic yard (27 cubic feet).

Always add 5% to 10% extra concrete to account for slab spillage, uneven ground excavation, and form deflection.

Standard concrete walkways and patios are 4 inches thick. Residential driveways are typically 4 to 6 inches thick with rebar reinforcement.

Concrete achieves ~70% strength in 7 days and full design strength at 28 days.

Cement is the binding powder ingredient; concrete is the hardened composite of cement, water, sand, and gravel aggregate.

3,000 to 4,000 PSI is standard for residential slabs, sidewalks, and driveways.

Control joints should be placed every 2 to 3 times the slab thickness in feet (e.g., every 8–10 feet for a 4-inch slab).