Materials calculator

Concrete Volume Calculator

Convert slab length, width, thickness, and waste allowance into cubic yards, bag counts, and ready-mix material cost.

Job inputs

How it works

Use the result as a checked starting point.

Concrete is ordered by cubic yard, while field dimensions are usually measured in feet and inches. This calculator performs the conversion and rounds ready-mix ordering to the next quarter-yard.

The bag estimates use typical approximate yields of 0.45 cubic foot for a 60 lb bag and 0.60 cubic foot for an 80 lb bag. Confirm the yield printed on the selected product before purchasing.

Cubic yards = length × width × (thickness ÷ 12) ÷ 27, then adjusted for waste.

Estimating checks

  • Measure average depth when subgrade varies.
  • Separate footings, thickened edges, piers, and steps into their own volumes.
  • Confirm minimum-load, delivery, short-load, and waiting charges with the supplier.

Common questions

Why add a waste allowance?

Spillage, uneven excavation, form movement, and measurement variation can increase actual volume.

Why round to a quarter-yard?

It creates a practical ordering figure, but your supplier’s increment and minimum may differ.

Does the price include labor or delivery?

No. The result multiplies order quantity by your entered price per yard only.