How we calculate
Every area follows a written rule. Here is the math, the standards we use per country, and how we keep them up to date.
· By the Squaremetry team
A room of 14′ 6″ × 12′ 0″
14.5 ft × 12 ft = 174 sq ft
- 14′ 6″ = 14.5 ft
- inches ÷ 12
- 14.5 ft × 12 ft = 174 sq ft
- length × width
- 174 sq ft × 0.0929 = 16.2 m²
- to square meters
The math
The math
-
Length times width
A = L × W
Each rectangle is measured and multiplied. Inches become decimal feet first.
-
Odd shapes in parts
A = A₁ + A₂ + …
L-shapes, bays and angled walls are split into rectangles and triangles.
-
Round at the end
≈ nearest 1 sq ft
We keep full precision and round only the totals you see.
Standards per country
The standards we use
Each mode follows the official text, in our own words. We note the version and the date we last checked it.
| Country | Standard | What it measures | Checked |
|---|---|---|---|
| United States | ANSI Z765-2021 | Gross living area, from the outside walls | Sep 2026 |
| Netherlands | NEN 2580 and the Meetinstructie | Gebruiksoppervlakte, inside the walls | Sep 2026 |
| Germany | Wohnflächenverordnung (WoFlV) | Living area, with sloped ceilings weighted | Oct 2026 |
| France | Loi Carrez and Loi Boutin | Private floor area of an apartment | to check |
| United Kingdom | RICS measuring guidance | Gross internal area | to check |
| Any other country | No national standard | Floor area inside the walls, no height rules | Oct 2026 |
Accuracy
As accurate as your tape
The math is exact. The result depends on how you measure: an error of 1 inch on a 12 ft wall changes that room by about 0.7%. For a listing, measure twice and use the outside walls.
How we keep the rules right
- Every rule is written down, with the source and version
- Every mode is tested against the worked examples in the standard
- A change to a rule gets a new version with a date
Ask the norm
Look it up in our guides
Every rule is explained in our own guides, with the version of the rules we use. Ask the norm, our assistant that answers only from these guides, is part of Pro.
- Read the guide →
Does a garage count?
What counts as finished living space, and what is listed apart.
- Read the guide →
ANSI Z765 in plain words
The rules for gross living area, step by step, with the version we use.
- See Pro →
Ask the norm with Pro
Ask a question in the editor and get an answer only from these guides, with the source.
Questions
Questions
About our method. Can’t find your answer? Send us a message.
info@squaremetry.comDo you round the areas?
We keep full precision while you draw and round only the totals you see, to the nearest square foot or 0.1 m².
Which standard should I use?
For a listing or an appraisal in the US, ANSI Z765. In the Netherlands, the meetinstructie, based on NEN 2580. For your own planning, the sum of the rooms is enough.
Can I see the formula for each room?
Yes. Select a room and Squaremetry shows its length, width and area, and the rule behind the number, such as a part under 5 ft that does not count.
How do you handle sloped ceilings?
Under ANSI Z765, parts lower than 5 ft do not count, and a floor counts only when at least half of it is 7 ft or higher. Under the Dutch meetinstructie, parts lower than 1.50 m do not count.
Who checks the rules?
The Squaremetry team writes each rule from the official text, in its own words, and tests it against the worked examples in the standard. Each rule has a version and a date.
How much does it cost?
The beta is free for 100 days, with up to 10 homes a month. After the beta: $5 per home for 30 days, or Pro for $19 a month or $149 a year, with 30 new homes a month.
Do I need an account?
No. You can draw and see every area without one; your plan stays in this browser. Sign in when you want to keep a home in your account or share it.
Can I export my floor plan?
Yes, as PNG, SVG or a PDF to scale, and as a square footage report with the rooms and the rule behind each number.
Does a garage count as square footage?
Not in the gross living area. A garage is not finished living space, so ANSI Z765 reports it separately, like a porch or a deck.
Can I measure in square meters?
Yes. Switch the units to meters and every length and area follows. Type 4.2 x 3.5 or 420 x 350 cm.
Start with your first floor plan
The beta is free for 100 days, with up to 10 homes a month. After the beta: $5 per home, or Pro from $19 a month.
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