Concrete Calculator

Calculate concrete volume for slabs, columns, tubes, curbs, and stairs. The calculator converts the chosen shape into cubic feet, then reports cubic yards, 80 lb bag count, total weight, and raw volume.

How to use this calculator

Select the shape tab, enter dimensions and units, and set quantity where available. Slabs accept length, width, height, and quantity. Columns use diameter and height. Tubes use outer diameter, inner diameter, and height. Curbs and stairs use inch-based detail dimensions.

Formula

For a slab, the core calculation is:

$volume = length \times width \times thickness \times quantity$

Then cubic yards are calculated as:

$cubic\ yards = cubic\ feet \div 27$

A 10 ft by 10 ft slab that is 4 inches thick has 33.33 cu ft of concrete, or 1.23 cubic yards. At 0.6 cu ft per 80 lb bag, that rounds to 56 bags.

Ordering concrete

Ready-mix orders usually need a waste allowance beyond the calculator output, especially for rough subgrade or forms that bow. For metric material and cost estimates, use the concrete volume calculator. For flatwork area checks, use the square footage calculator.