Square Footage Calculator: Easily Measure Room Area for Any Shape
This calculator multiplies your room’s length × width—or uses π r² for circles—to return square feet and square metres in seconds. Enter feet and inches; the script converts inches to decimal feet, preventing manual errors. A 22 ft 3 in circular sunroom equals roughly 389 sq ft, or 36 sq m. Average U.S. living rooms measure 330 sq ft (National Association of Home Builders, 2022).
Room Square Footage Calculator
Result
Tip: Enter measurements in feet and inches. For best results, round to the nearest inch.
★ Add to Home Screen
×
Follow these steps:
Tap the Share button at the bottom of the browser
Scroll down and tap “Add to Home Screen”
Tap “Add” to confirm
Follow these steps:
Tap the menu icon (⋮) in the top right
Tap “Add to Home screen”
Tap “Add” to confirm
Follow these steps:
Click the menu icon (⋮) in the top right
Click “Bookmarks”
Click “Bookmark this tab” or press Ctrl+D (Cmd+D on Mac)
Is this tool helpful?
Thanks for your feedback!
How to use the tool
1 Select a shape
Rectangle/Square
Circle
L-Shape
2 Enter your dimensions
Use feet and inches fields; inches convert automatically.
Sample 1 (Rectangle): Length 14 ft 8 in, Width 11 ft 5 in.
Sample 2 (Circle): Diameter 22 ft 3 in.
3 Press “Calculate Square Footage”
The result appears immediately, showing square feet and square metres.
Formulas the script applies
Decimal feet = feet + inches/12
$$A_{rectangle}=L
ac W$$
$$A_{circle}=π
ac\left(\dfrac{D}{2}\right)^2$$
$$A_{L}=L_1
ac W_1 + L_2
ac W_2$$
Example calculations
Rectangle sample: 14.67 ft × 11.42 ft = 167.5 sq ft → 15.56 sq m.
Circle sample: Radius 11.125 ft → A = π × 123.77 = 388.7 sq ft → 36.1 sq m.
It finds the two-dimensional area of rectangles, circles, and L-shapes, outputting square feet and square metres for material estimates (ICC, 2021).
How do I convert inches to decimal feet?
Divide inches by 12. Example: 7 in ÷ 12 = 0.58 ft. Add to the feet value before multiplying dimensions (NIST, 2022).
Why does the tool show both units?
U.S. projects rely on square feet; international teams and scientific specs use square metres, so dual output avoids extra conversions (ISO 80000-1, 2019).
How accurate is the result?
The script uses number inputs limited to two-decimal precision and JavaScript’s double-precision floats, giving ~0.01 sq ft accuracy—adequate for residential work (Mozilla Developer Network, 2023).
How is an L-shape handled?
It splits the room into two rectangles, calculates each area, then adds them: $$A_{L}=L_1W_1+L_2W_2$$ This mirrors professional take-off practice (ASHRAE Handbook, 2021).
Can I use it for patios or decks?
Yes—outdoor flooring or paint needs square footage just like interiors. Enter the exterior dimensions and apply exterior-grade material factors (EPA “Decking Guide,” 2022).
What waste allowance should I add?
Most flooring suppliers recommend 5–10 % overage for cuts and defects; carpet rises to 10 % for seam matching (Interface Carpet Estimator, 2022).
Is there a maximum room size?
Browser number fields accept up to 1e308, but practical use stays below 10,000 sq ft for single rooms; larger areas are typically sectioned (BOMA Floor Measurement Standard, 2019).
Important Disclaimer
The calculations, results, and content provided by our tools are not guaranteed to be accurate, complete, or reliable. Users are responsible for verifying and interpreting the results. Our content and tools may contain errors, biases, or inconsistencies. We reserve the right to save inputs and outputs from our tools for the purposes of error debugging, bias identification, and performance improvement. External companies providing AI models used in our tools may also save and process data in accordance with their own policies. By using our tools, you consent to this data collection and processing. We reserve the right to limit the usage of our tools based on current usability factors. By using our tools, you acknowledge that you have read, understood, and agreed to this disclaimer. You accept the inherent risks and limitations associated with the use of our tools and services.
