Exterior Calculators

Working with exterior quantities

Exterior work is measured by perimeter and area, but the failures are almost always about water rather than quantity. Siding, decking and retaining walls all depend on a working drainage path behind or beneath them — get the quantity right and the drainage wrong, and the material choice barely matters.

Worth knowing: Measure the perimeter at ground level, then add each gable separately as half its base times its height. Gables are the area people forget.

These 5 calculators cover about 19,810 searches a month between them. Every one prints the formula it uses and a worked example, so you can check the result by hand before you order.