About PorchMath

PorchMath is a free collection of material calculators for homeowners and DIYers. Each tool shows the formula it uses, a worked example and practical tips, so you can understand—and double-check—every estimate.

How we build our calculators

Formulas are standard geometry (area and volume) combined with typical material data such as bag yields, coverage rates and densities. Where numbers vary by product, the calculator lets you enter the value from your product label.

Accuracy

Results are estimates. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions.