Rectangular slab volume and purchase planning.
Slab length, width, thickness, waste and product yield.
Raw volume, ordering allowance, cubic yards and package options.
Thickness and reinforcement are design decisions; the calculator does not approve them.
See the estimated project quantity from your measurements.
Add waste and round to complete bags, boxes, cans, bundles or delivery quantities.
Review product coverage, site conditions, local requirements and supplier details before ordering.
Estimate slab volume, cubic yards, and an 80-lb bag equivalent before you order material.
Thickness is converted from inches to feet, then length × width × thickness gives the base volume. The calculator adds the selected overage after calculating the base quantity.
A 20 ft × 10 ft slab at 4 in thick is about 66.7 ft³, or 2.47 yd³ before waste. With 7% overage, the planning quantity is about 2.64 yd³.
Ready-mix suppliers normally quote by cubic yard. Confirm yield, minimum load, delivery rules, reinforcement, subgrade and final field measurements.
Thickness depends on loads, soil, reinforcement, climate and applicable requirements. This tool calculates volume; it does not design the slab.
Uneven subgrade, forms, spillage and measurement differences can create a shortage. Use an allowance that fits the project.
This page defaults to US customary units because concrete ordering is commonly quoted in cubic yards in the US.