Concrete Calculator

How to use this calculator

Enter Length (ft), Width (ft), Thickness (in). The result updates in your browser as you edit an input. The prefilled values are examples only.

How the estimate works

Multiply length and width by thickness converted to feet. Divide cubic feet by 27 for cubic yards.

What can change the answer?

This is geometric slab volume only. Uneven ground, thickened edges, formwork, and spill allowance increase the quantity needed. Confirm thickness and specifications for the project.

Before relying on the result

Use feet for length and width, and inches for thickness. The result is rectangular geometric volume; uneven excavation, thickened edges and order allowances require separate calculations. Confirm the project specification and supplier’s yield or delivery units. This tool does not select thickness or reinforcement.

Worked example with the default inputs

A slab 12 feet by 10 feet by 4 inches has a volume of 40 cubic feet, or 1.48 cubic yards. Four inches is one third of a foot; entering four feet would greatly overstate the order.

Interpret the result in a planning record

A slab’s area alone does not tell you the volume of concrete. Enter its length and width in feet and thickness in inches. The concrete calculator converts the depth to feet and reports cubic yards. Thickened edges and uneven excavation need separate treatment; the geometric volume is a starting point for discussing the order with your supplier.

Save the input values, units and result together. Change one uncertain input at a time so you can see which assumption moves the answer. A displayed decimal is arithmetic precision, rather than evidence that the measurements or rates are equally precise.

More tools

Read the How to Measure a Project Before Buying Materials guide →