Construction calculator

This works out a concrete pour the way the order is placed. Length times width times thickness over twelve is the cubic feet; over twenty-seven is the cubic yards; your waste and over-excavation allowance on top is the yards to order; and the order at your supplier's delivered price is the concrete line. Every figure is yours; the tool publishes no price and no allowance. Free, on the page, no account; the paid plan saves each worked pour against the project.

Cubic feet over twenty-seven is the yards

A slab's volume is its length times its width times its thickness, with the thickness in inches divided by twelve to bring it to feet, and a cubic yard is twenty-seven cubic feet. The tool shows the cubic feet and the exact yards separately so the arithmetic can be checked against the plan, and so a thickened edge or a footing can be worked as a second pour and added.

Waste is your allowance, and it goes on before the order

An uneven subgrade, a form that bows and the concrete left in the chute all take yards the plan does not show. The allowance is a percentage you set from your own pours, shown as the difference between the exact yards and the yards to order, because ordering exact and coming up half a yard short costs a second truck and a cold joint.

At your supplier's price, the concrete line for the estimate

The yards to order times the delivered price on your last ticket is the concrete line, and it is the figure that goes into the estimate. The tool asks for the price because concrete is quoted by the plant and the mix, and a price published on a website is a guess about a plant nobody has called. The paid plan keeps the pour against the project.