Square footage calculator
This is the plain area of the shape you enter. It does not deduct openings or add waste — bring the area to a material tool for that, and measure twice before you order anything from it.
Pick a shape, enter the dimensions, and you get the area in square feet and square metres at the same time. A rectangle is length × width; a circle is π × radius². The "how many" field totals several identical areas in one go.
Worked example
A bedroom 12 ft × 10 ft is 12 × 10 = 120 square feet. To read that in metric, multiply by 0.0929: 120 × 0.0929 ≈ 11.15 m². Two identical bedrooms would be 240 sq ft. A round patio 10 ft across is π × 5² ≈ 78.5 sq ft.
The formula
rectangle: area = length × width · circle: area = π × (diameter ÷ 2)²
Area is a length times a length, so its unit is a square: feet × feet gives square feet. Converting to metric squares the length factor too, which is why the number is 0.0929 per square foot rather than 0.3048.
Questions
- How do I calculate square footage?
- Multiply length by width for a rectangle. A 12 ft by 10 ft room is 120 square feet. For a circle, it is π times the radius squared — or use the diameter option here and let the tool do it. For an L-shaped room, split it into rectangles, work out each, and add them together.
- How do I convert square feet to square metres?
- Multiply square feet by 0.0929, or divide by 10.764. This tool shows both at once, so a 120 sq ft room reads as about 11.15 m² without you touching a conversion. The factor is just the square of the foot-to-metre ratio (0.3048² = 0.0929).
- Do I subtract doors and windows?
- It depends what the area is for. For flooring, work with the full floor area. For wall paint or drywall, subtract large openings if you want a tighter number, though many people leave them in as built-in waste. This tool gives you the gross area; subtract openings yourself where it matters.
- How much extra should I add for waste?
- Square footage itself is just the measurement, so this tool does not add waste — it gives the true area. Add the waste on the material tool instead: flooring, tile and drywall calculators apply a waste factor to the area you bring them.
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