Floor area calculator, room by room
Enter each room’s length and width from the plan or a tape measure. The total updates as you type, in square metres and square feet.
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How the floor area is worked out
Each room is length × width, measured from the inside face of one wall to the inside face of the opposite one. Add the rooms together and you have the flat’s internal floor area, the figure most floor plans write inside each room and the one to compare between flats.
Rooms that aren’t rectangles are split: an L-shaped living room is two rectangles, a room with a chimney breast is the full rectangle minus the breast. Enter each part as its own row.
Listings often quote a larger gross figure measured over the walls, or one that includes balconies or common parts. For the definitions and how to check a listing’s number, see how to measure floor area; for what each room usually measures, standard room sizes.
Questions, answered
How do I calculate the floor area of a room?
Multiply its length by its width, both measured wall to wall: a room 4 m by 3.5 m is 14 m². For an L-shaped room, split it into two rectangles, work out each and add them.
How do I calculate the floor area of a flat from its plan?
Read each room’s length and width from the plan’s dimension lines, enter them here as one row per room, and the total is the flat’s usable floor area. Measured over the walls instead, the same flat typically comes out 5–10% larger: that is the gross figure many listings quote.
How many square feet is a square metre?
1 m² is 10.764 sq ft, and 1 sq ft is 0.0929 m². So a 50 m² flat is 538 sq ft, and a 1,000 sq ft flat is 92.9 m².
Do balconies count in the floor area?
Usually not in the internal area: UK and Polish rules leave them out, and plans list them separately. Some markets, Dubai among them, include them in a saleable area, so check which figure a listing gives.
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