Construction

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Square Footage Calculator.

Calculate area for flooring, painting, and construction

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How to Use

Calculate the total square footage of rooms or areas for:

  • Flooring installation
  • Paint coverage estimation
  • Carpet requirements
  • Property measurements

Add multiple rooms to calculate total area for entire projects.

Cite this calculator

Canonical URL: https://mathify.one/fr/construction/square-footage

Cite as: Mathify. (2026). Calcul de Surface. https://mathify.one/fr/construction/square-footage

Use Cases

Flooring Installation

Determine the amount of flooring material needed for a room or entire house. Enter the room's length and width to get the square footage, then order the right quantity of tiles, hardwood, or carpet.

Example: A 15 ft × 20 ft living room = 300 sq ft, so you'd need at least 300 sq ft of flooring.

Painting Projects

Estimate the wall area to paint. Measure the length and height of each wall, calculate the square footage, and subtract areas for doors and windows to find the paintable surface.

Example: A wall 12 ft long and 8 ft high = 96 sq ft, minus a 20 sq ft window = 76 sq ft to paint.

Frequently Asked Questions

How do I calculate square footage?
Measure the length and width of the area in feet, then multiply them together (length × width). For example, a room 12 feet long and 10 feet wide is 120 square feet. If the area is not a perfect rectangle, divide it into rectangular sections, calculate each, and sum them.
What units does the calculator use?
The calculator uses feet for length and width, and outputs area in square feet. Ensure all measurements are in feet before entering them. If you have inches, convert to feet by dividing by 12 (e.g., 6 inches = 0.5 feet).
Can I use this for irregularly shaped rooms?
Yes, but you'll need to break the room into smaller rectangles. Measure each rectangle's length and width, calculate its square footage, and add them together. For complex shapes, consider using a professional measurement service.

Tips & Common Mistakes

Tips

  • Measure to the nearest inch for accuracy, then convert to feet (divide inches by 12).
  • For irregular rooms, divide into rectangles and calculate each separately, then sum.
  • Always add 10% extra to your square footage for waste, cuts, and mistakes.
  • Double-check your measurements before entering them to avoid ordering too little material.

Common Mistakes to Avoid

  • Forgetting to convert inches to feet before multiplying, leading to incorrect results.
  • Measuring only one dimension and assuming the room is square, which overestimates or underestimates area.
  • Not subtracting areas for doors, windows, or built-ins when calculating paintable surface.

Last updated: August 13, 2026