Room Area & Square Footage Calculator
Enter a room’s length and width to get its floor area in square metres and square feet — add a second rectangle for an L-shaped room, and read off the perimeter too.
Floor area
Perimeter is shown for a simple rectangle only. For an L-shaped room the two rectangles are summed; measure the alcove as the smaller rectangle that completes the L.
Start every plan with the floor area
Floor area is the number almost every other decision hangs on. It sets how much flooring to order, roughly how much paint the walls will take, whether a sofa and a table can share the space, and what a room is worth per square metre. Getting it right at the start saves guesswork — and returns — later.
Measure wall-to-wall at floor level rather than off a listing or an old plan, which can round or simply be wrong. For anything but a plain rectangle, break the floor into rectangles you can measure cleanly and let the tool sum them.
Frequently Asked Questions
How do I calculate the area of a room?
For a rectangular room, multiply the length by the width. A room that is 5 metres long and 4 metres wide has a floor area of 20 square metres. This calculator does that for you and also converts the result to square feet, so you can use whichever unit a supplier or plan quotes in.
How do I measure an L-shaped room?
Split the floor into two rectangles: the main rectangle and the smaller alcove that completes the L. Measure each one, and the calculator adds the two areas together. Tick the L-shaped option and enter the alcove's length and width. The same approach scales to any shape you can break into rectangles.
Should I measure in metres or feet?
Use whichever you find easier — the tool reports the area in both square metres and square feet regardless. Flooring and paint are often sold by square metre in some markets and square foot in others, so having both figures saves a conversion step at the shop.
What is the perimeter used for?
The perimeter — twice the length plus twice the width — is the total run around the walls at floor level. It's what you need for skirting board, coving, or a border, and it feeds the wall-area step of a paint estimate. The perimeter is shown for a simple rectangle; for an L-shape, measure the wall runs directly.
Do I subtract things like a chimney breast or bay?
For flooring, yes — subtract a chimney breast or built-in cupboard footprint, since you won't lay floor there, and add a bay as a small extra rectangle. For a quick capacity or paint estimate, the plain rectangle is usually close enough. When in doubt, measure the awkward bits separately and adjust.
A general estimate from the dimensions you enter. Always measure on-site before ordering materials, and for load-bearing, structural, or permit-related work consult a qualified professional.