How to calculate square feet
For a rectangle, multiply length by width. A 12 ft × 10 ft room is 120 square feet.
1. Measure length
Measure the longest side of the room or project area in feet. If you measure in feet and inches, convert the inches to a decimal of a foot before multiplying.
2. Measure width
Measure the second dimension using the same unit. For a rectangular area, these two measurements are all you need.
3. Multiply length × width
The square-foot formula is length × width = area. For example, 12 ft × 10 ft = 120 sq ft.
4. Handle irregular areas
Split an L-shaped or irregular space into rectangles, calculate each rectangle separately, then add the square-foot totals together.
5. Add waste for materials
Flooring, tile and other cut materials often need extra for offcuts and damaged pieces. Use a waste allowance that suits the product and layout.
Need the calculator?
Use the Square Footage Calculator on the homepage for an instant result, waste allowance and optional cost estimate.