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Room Area Calculator — floor area in square metres (m²)

Floor area is the fundamental metric for any property — it drives purchase price, finishing costs, service charges and property tax. In Poland the applicable standard is PN-ISO 9836, which requires area to be measured between finished wall surfaces, excluding wall thickness. This calculator supports three modes: Rectangle for a standard square or rectangular room, L-shape for a room with an alcove or recess, and Whole apartment to add up to 5 separate rooms. The result is the net usable floor area (PUM) in m². Usable floor area (PUM) is the sum of all habitable rooms: living rooms, kitchen, bathroom, toilet, and hallway. Balconies, loggias and terraces are typically excluded from PUM. Always verify what is included in the quoted m² figure in the sale agreement or title deed. Enter each room's dimensions in metres, choose the mode and click Calculate — the calculator instantly returns each room's area and the grand total.

Reviewed byRedakcja Liczbnik
Calculator
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Floor area (m²)Room 1 area (m²)20
Total floor area (m²)
20

How we calculate floor area

Rectangle: area = length x width. L-shape: area = (l1 x w1) + (l2 x w2). Divide the room into two rectangles and measure each separately. Whole apartment: total = P1 + P2 + P3 + P4 + P5, where each Pi = length_i x width_i. All results are rounded to 0.01 m². Negative or zero values are treated as 0.

Example: 3-room apartment, L-shaped living room + 2 bedrooms

L-shaped living room: rectangle 1 = 5 m x 4 m = 20 m², rectangle 2 = 2 m x 3 m = 6 m², total 26 m². Bedroom 1: 4 m x 3 m = 12 m². Bedroom 2: 3.5 m x 3 m = 10.5 m². Subtotal (without bathroom and kitchen) = 48.5 m². Adding bathroom (6 m²), WC (2.5 m²), kitchen (9 m²) and hallway (4 m²), total usable area = 70 m².

Frequently asked questions

How do I calculate the area of a rectangular room?

Multiply the room's length by its width: area = length x width (in metres). The result is in square metres (m²). Example: a room 4.5 m x 3.2 m = 14.40 m².

What is PUM and how does it differ from gross floor area?

PUM (Powierzchnia Uzytkowna Mieszkania — usable floor area) is the sum of all habitable rooms: living rooms, kitchen, bathroom, toilet and hallway. Balconies, loggias, terraces and utility rooms are usually excluded. Gross floor area may be higher if developers include a share of common areas. Always check exactly what the quoted m² figure covers in the sales listing.

Does the GUS (Polish statistics office) include walls when measuring apartments?

Under the PN-ISO 9836 standard used by GUS, area is measured between finished wall surfaces (not in the axis of walls), so internal wall thickness is excluded. Alcoves and fitted wardrobes are included if their depth exceeds 20 cm.

How do I calculate the area of an L-shaped room?

Divide the L-shaped room into two rectangles, calculate the area of each and add the results. Example: rectangle 1 = 4 m x 5 m = 20 m², rectangle 2 = 2 m x 3 m = 6 m², total = 26 m². The calculator does this automatically when you select the L-shape mode.

What is the average apartment size in Poland?

According to GUS data, the average usable floor area of a dwelling in Poland is around 72-75 m² (existing stock). New completions average around 55-65 m². A studio is typically 20-35 m², a two-room flat 40-55 m², a three-room flat 55-75 m², and four rooms and above exceed 75 m².

How do I calculate the floor area of an entire apartment?

Measure each room separately (length x width) and sum the results. Include the kitchen, bathroom, toilet, hallway and any pantry — all count towards PUM. The Whole apartment mode accepts up to 5 rooms and sums their areas automatically.

Indicative result

Results are indicative. Depending on the measurement method and applicable standard, values may differ from those stated in the sale agreement or title deed. This calculator does not replace a professional architectural survey or geodetic measurement.
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