Square Footage Calculator
Calculate square footage from length and width for flooring, paint, mulch, and room planning. Free sq ft calculator.
How to use this square footage calculator
Flooring, paint, HVAC rules of thumb, and mulch all start with square feet. Measure length and width of a rectangle. For L-shapes, split into rectangles and add. Then open the concrete, mulch, or HVAC calculator if you need volume or load.
Formula
Worked example
A 12 ft by 10 ft room is 120 square feet.
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Frequently asked questions
Is this square footage calculator free?
Yes. It works instantly in your browser with no signup.
Are the results exact?
Results follow the stated formula, but real-world fees, timing, and rounding can vary.
How do I calculate square footage?
Multiply length by width in feet. A 12×10 room is 120 square feet. Add rooms for a whole-floor total.
How much flooring do I need?
Start with square footage, then add 5–10% waste (more for diagonal layouts or lots of cuts).
Square feet vs cubic feet?
Square feet is area (length × width). Cubic feet is volume (area × height). Use the concrete or mulch tools for volume.
How do I measure an L-shaped room?
Split it into two rectangles, calculate each, and add. This calculator handles one rectangle at a time.
Results are estimates for informational purposes and are not financial, legal, or professional advice. Last reviewed 2026-08-20.