Square Feet Calculator
Calculate square feet for rectangles, triangles, circles and multi-room projects.
ft
ft
%
$/sq ft
Total square footage
100 sq ft
- Area 1
- 100 sq ft
How we calculate this
For a rectangle: length × width. For a triangle: base × height ÷ 2. For a circle: π × radius². Add multiple areas together for an irregular room or multi-room project.
Example
A 12 ft × 15 ft room is 180 square feet. Add a 6 ft × 4 ft closet (24 sq ft) and the total is 204 square feet.
Common mistakes
- Measuring along baseboards or trim instead of wall-to-wall, which undercounts the true area.
- Forgetting to add closets, alcoves, or other small sub-areas to the total.
- Mixing up square feet (area) with linear feet (length) when ordering flooring or trim.
Frequently asked questions
How do I calculate square feet of a room?
Multiply the room’s length by its width, both measured in feet. For irregular rooms, break the space into rectangles, triangles, or circles and add each section together.
How many square feet is a 10x10 room?
100 square feet — multiply the two measurements directly.
Related calculators
Estimates are provided for planning purposes. Actual material requirements may vary based on supplier specifications, compaction, site conditions, installation method, waste, and local code.