Trade Math · Square Feet

Calculating total square feet

Area shows up whenever you're ordering flooring, figuring tile, or sizing a roof patch. The formulas are short; the mistakes are where points go. Here's the rectangle, the triangle, the circle, and how to handle the composite shapes that make up real rooms.

Cheat sheet

  • Rectangle: Area = L × W
  • Triangle: Area = (1/2) × base × height
  • Circle: Area = π × r² (π ≈ 3.14)
  • Composite shapes: split into sub-rectangles and add, OR start from the bounding rectangle and subtract what's missing.
  • Unit conversion: 1 sq ft = 144 sq in (12 inches × 12 inches).

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