Area, perimeter, and material-cost example
For a rectangular room, area is length multiplied by width. If both measurements are in feet, the result is in square feet (ft²). Perimeter is the total distance around the boundary: twice the length plus twice the width. Perimeter is a length, not an area, so its unit is feet.
Worked example
A rectangular room that is 12 ft long and 10 ft wide has an area of 12 × 10 = 120 ft² and a perimeter of 2 × (12 + 10) = 44 ft. If a material is priced at $3 per square foot, 120 ft² corresponds to $360 before taxes, delivery, labor, waste, or minimum-order charges.
Measure carefully
- Measure length and width in the same unit before multiplying.
- For an L-shaped or irregular space, split it into rectangles, calculate each area, and add the pieces without double-counting overlap.
- Material orders often need extra coverage for cuts, pattern matching, and damaged pieces. Use the supplier's advice and the material packaging to choose the allowance rather than treating the raw area as the exact order quantity.
This estimate assumes a flat rectangular footprint. It is not a substitute for a detailed takeoff for stairs, angled walls, unusual layouts, or commercial work.
Tips for accurate results
Break an irregular space into rectangles and triangles, calculate each area, and add them. Measure in the same unit throughout and convert inches to feet by dividing by 12. Remember that one square yard is 9 square feet.
Common mistakes and limits
For flooring, paint, or sod, buy extra material to allow for cuts and waste, often 5 to 10 percent or more for complex layouts. Subtract large openings only if you are sure you will not need that material. Measure twice before ordering.