How to calculate square footage without making the usual mistakes.
Square footage is usually length times width, but real rooms and projects often include closets, alcoves, jogs, angled areas, waste, and material rounding.
The basic method
- Measure the length.
- Measure the width.
- Make sure both measurements use the same unit.
- Multiply length by width.
- Add overage if you are buying material.
Odd-shaped rooms and floor plans
For L-shaped rooms, closets, alcoves, hallways, or floor plans with multiple rectangles, split the shape into smaller rectangles. Calculate each section separately, then add the areas together.
Rooms
Include closets and alcoves when ordering flooring, carpet, tile, or paint for those areas.
Walls
Use wall length times wall height, then subtract large openings only when you need a tighter material estimate.
Materials
Square footage is the starting number. Boxes, rolls, sheets, bags, and bundles still need waste and rounding.