Area & Layout Calculators

How a Room's Floor Area and Perimeter Are Calculated

A rectangular room's floor area is length times width, and its perimeter — the total distance around all four sides — is twice the sum of length and width, a figure that turns out to be the starting point for estimating wall area too.

How a Room's Perimeter Becomes Its Total Wall Area

Feeding a room's real perimeter into the wall area calculator as the wall length gives the combined area of all four walls at once, rather than one wall at a time — a real shortcut for estimating paint or plaster for an entire room.

How a Wall's Net Area Is Calculated for Paint and Plaster

A wall's gross area (length times height) overstates what actually needs painting or plastering — subtracting the combined area of doors and windows gives the net area that material quantities should actually be based on.