Floor plan square footage calculator
Add room areas from a calibrated floor plan, switch square metres and square feet, and check that the rooms sum to the total.
Worked examples
Each control loads that case on the sheet. The figures are the ones the scale, the outline, or the waste setting produces. They are not sample captions pasted over a different result.
Free files are a PNG, a table PDF, CSV, DXF and a project file. No account and no watermark. The pass, the month and the lifetime unlock an auto-dimension PDF, an auto-dimension SVG, and a takeoff zip with a signature page. Every paid line prints its formula. No prices and no tin counts.
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Skirting is the perimeter minus the door width you traced. Leaders are drawn only on segments you have already traced.
Living floor 3.30 m²
Skirting net 6.20 m
Paint, one coat 16.72 m²
Living room floor 3.00 m² x 1.10. Skirting 7.00 m - 0.80 m. Paint (7.00 m x 2.40 m - 0.80 m x 2.00 m) x 1.10.
Results depend on drawing quality, the calibration length, and where you trace. They are not a substitute for measuring on site, a statutory valuation, or a professional quantity survey.
How the numbers are produced
This page is the area sum, not the tracing lesson. It opens on Elm Cottage at the known 2.00 m wall. Living room 3.00 m² plus kitchen 1.80 m² is the total 4.80 m². The total is the sum of the net room areas on the current page. A void you have already subtracted inside a room is not added again. Rooms on another PDF page are not in this total until you switch to that page.
Feet use the same trace. Press Feet and the 2.00 m wall reads 6.56 ft. The living room reads 32.29 ft², the kitchen 19.38 ft², and the total 51.67 ft². The conversion is 1 ft = 0.3048 m, then half away from zero to two decimal places. You do not trace the rooms again. Press Metres and the figures return to 2.00 m, 3.00 m², 1.80 m², and 4.80 m². Square feet are the metre area divided by 0.3048 squared, which is 0.09290304. 4.80 / 0.09290304 is 51.666…, which rounds to 51.67 ft².
At 1:100 the same pixels are a larger building. The 400 pixel reference is 4.00 m. Living room area is four times 3.00 m², which is 12.00 m². The kitchen is 7.20 m². The total is 19.20 m². In feet that total is 206.67 ft². Lengths doubled because the ratio doubled from 1:50 to 1:100. Areas quadrupled because area uses the square of the scale factor. A 10 percent error in a wall length is about a 21 percent error in the area of a rectangle. That is why the calibration warning at 5 percent exists on the editing desk before you trust a total.
Zoom does not change the area. One zoom-in sets the view to 200 percent and leaves 4.80 m² where it was. A wider window does not change it either. The area changes only when the scale changes or an outline changes. Moving living room corner 2 from y 400 to y 300, which is a check on the measurement-tool page, drops the living room to 2.50 m² and the total to 4.30 m². Undo restores 4.80 m². This page’s examples reload the three published sums: metres, feet, and the 1:100 total.
Net area is the inside of the outline you traced. It is not a code of measuring practice and it is not a statutory valuation. If you traced the inside face in the living room and the centreline in the kitchen, the total mixes two faces. Trace the same face in every room you intend to add. A stair opening is a void, subtracted inside that room, which is what the room-area page demonstrates with a 1.00 m² void turning 12.00 m² into 11.00 m². This total will include that net figure once, not the gross and the void as separate rooms.
The free floor line can take 5, 10, or 15 percent waste, but the area fields on this page stay net. At 10 percent the living room floor order is 3.30 m², shown in the preview under the sheet, while living-area still reads 3.00 m². At 1:100 the floor order is 13.20 m² and the net skirting before waste is 12.40 m. The preview is open so you can see the waste line without leaving the area. The paid pack prints the formula; this page’s job is to show that the rooms add up.
Where these figures get used
A buyer comparing two rooms on a 1:50 plan can read 3.00 m² and 1.80 m² and see the total 4.80 m² without adding them by hand. Switching to feet gives 32.29 ft², 19.38 ft², and 51.67 ft² for the same outlines. The arithmetic is the check: if the two rooms do not sum to the total, a room was left untraced or a void was counted twice.
A designer reprinting at 1:100 can load that example and expect 19.20 m², which is 206.67 ft². If their title block says 1:100 but a known wall of 2.00 m on a 400 pixel line gives 4.80 m², the printed ratio and the wall disagree. Believe the wall you can measure on site, and read the 40 mm table on the floor plan dimensions page before you mix 1:100 with 1/4 in = 1 ft. Those are 1:100 and 1:48, not the same scale.
An area schedule that will be handed to a surveyor should say it is the outline you traced. This total is not net internal area under a measuring code. The disclaimer under the downloads says the result is not a substitute for measuring on site, a statutory valuation, or a professional quantity survey. Use the figure to brief someone. Do not paste it into a valuation as if it were a measured survey.
Offset leaders, the 40 mm scale table, and the 1.92 m versus 2.00 m gap are drawn on the floor plan dimensions page.
Common questions
How is the total area calculated?
It is the sum of the net room areas on the page. A void you marked is already subtracted from that room. It is not added again.
How do square metres become square feet?
The tool converts the metre result with 1 foot = 0.3048 metres, then rounds half away from zero to two decimal places. You do not trace the room again. Elm Cottage is 4.80 m², which is 51.67 ft².
Does zoom or a bigger window change the area?
No. View zoom, PDF zoom and screen zoom do not change the calibration. The area changes only when the scale or the outline changes.
Is this the same as a surveyor's net internal area?
No. You get the area inside the outline you traced. It is not a statutory valuation and it does not apply a code of measuring practice on its own.
The rest of the desk
Each of these opens the same measuring rules on a different job. Calibration is shared. A scale you set on one page is not stored for the next visit.