Measurement guide
How to calculate square footage of a room
Square footage is the area of a floor, wall, or ceiling measured in square feet. For a rectangle it is length × width. Everything else is a matter of splitting the space into shapes you can multiply.
Rectangles and squares
A 12 × 10 ft bedroom is 120 sq ft. A 12 × 12 ft room is 144 sq ft. If your tape reads in feet and inches, divide the inches by 12 first: 11 ft 6 in is 11.5 ft.
L-shaped and irregular rooms
- Sketch the room and draw a line that splits it into rectangles.
- Measure the length and width of each rectangle.
- Multiply each pair and add the results.
For example, an L made of a 14 × 12 ft living area and a 10 × 8 ft dining nook is 168 + 80 = 248 sq ft. Check that the split line does not count any strip twice.
Triangles and angled walls
Bay windows and angled corners can usually be split into a rectangle and one or two triangles. Calculate each and add them.
Converting units
| From | To | Do this |
|---|---|---|
| Square feet | Square yards | ÷ 9 |
| Square feet | Square meters | × 0.09290304 |
| Square meters | Square feet | × 10.7639 |
| Square inches | Square feet | ÷ 144 |
Floor, wall, or ceiling?
Floors and flat ceilings share the same square footage. Walls are different: multiply the perimeter by the wall height, then subtract doors and windows. The wall area calculator does that, and the room size calculator shows floor, ceiling, walls, and volume together.
Measuring tips
- Measure wall to wall at floor level.
- Round each dimension up to the next inch, not down.
- Measure twice, especially in older homes where walls are rarely square.
- Add closets and alcoves that will receive the same material.