Square Footage Calculator

Add as many sections as you need — rectangles, circles, triangles or a known area — and get the total in square feet, square metres and square yards.

Useful for flooring quotes, paint coverage, land measurements and anything priced per square foot. Add a rate and it returns the cost too.

How to use the square footage calculator

Why use the Build Tally square footage calculator

How to measure a room properly

Measure at floor level, along the finished wall face, and take each wall to the nearest inch rather than the nearest foot. Rooms are rarely perfectly square, so if two opposite walls differ, measure both and use the larger for material and the smaller for fit. For an L-shaped or open-plan space, do not try to average it: split it into rectangles at the internal corner, calculate each one and add them, which is exactly what the add-section button here is for.

Converting between area units

One square yard is 9 square feet, and one square metre is 10.764 square feet. Carpet is often sold by the square yard, tile and laminate by the square foot or the box, and almost everything outside North America by the square metre. Land is measured in acres — 43,560 square feet — or hectares at 10,000 square metres. The calculator shows the common units side by side so you can match whichever one your supplier quotes in.

What to include and what to leave out

For flooring, include every part of the floor that will be covered, including under kickboards where the floor runs through, and closets if they are being floored. Exclude fixed islands and built-in cabinetry that sits on the subfloor. For a paint job, the number you want is wall area, not floor area — length plus width, doubled, times the ceiling height, then deduct doors and windows. The paint calculator handles that conversion for you.

Read the guide: How to Calculate Square Footage of a Room, a House or a Yard