Which calculator do I need?
Start with the square footage calculator when you need the area of a typical room, several rooms, or a space that can be divided into measured sections. It accepts common shapes and units, so it is the right first step when you have dimensions but have not yet chosen a material.
Use the L-shaped room calculator when the space has one rectangular missing corner and you want a focused outside-minus-cutout calculation. For other irregular layouts, divide the outline into non-overlapping pieces in the main room calculator; make sure no floor area is counted twice.
Choose the flooring calculator after you know the net floor area and want to estimate whole boxes. Enter the coverage printed on the package and an allowance appropriate to the product and layout; the tool rounds the package count up. The tile calculator estimates tile and package quantities from tile dimensions and coverage.
Use the wall area calculator for a vertical surface: multiply its width by height, then subtract doors and windows that will not be covered. It estimates surface area, not the number of paint gallons.
The conversion pages help when a quote or product listing uses a different area unit. Convert after calculating the area, and keep the original dimensions and package label nearby. If you are not sure how to measure the space, read the room guide before estimating a material quantity.