Square Footage Calculator
Use our square footage calculator to calculate square footage for rooms and spaces. Includes square footage explained, how square footage is calculated, square footage formulas for common shapes, and examples like how big 300 sq ft is.
Square Footage Explained
Square footage (sq ft or ft²) is a measure of area—how much surface a floor (or any flat space) covers. It’s used for room sizes, flooring estimates, real estate listings, and renovation planning.
To calculate square footage, you measure the length and width of the space (in feet) and multiply them. For irregular rooms, you can split the floor plan into smaller rectangles and add them up.
This square footage calculator helps you figure out square footage quickly for common room layouts.
Square Footage Formula
Square footage is area measured in square feet. The formula depends on the shape of the space.
Most rooms can be measured as a rectangle (or split into rectangles).
Useful for angled spaces; keep units in feet.
r is radius in feet.
Break the shape into rectangles/triangles, calculate each, then add them.
A common bedroom-sized rectangle.
How to Calculate Square Footage
- 1
Measure the length and width of the room (in feet).
- 2
If you measured inches too, convert inches to feet (divide inches by 12) and add to the feet value.
- 3
Multiply length × width to get square footage (ft²).
- 4
For an L-shaped or irregular room, split it into smaller rectangles, calculate each area, and add them together.
Frequently Asked Questions
For a rectangular room, square footage is length × width (both in feet). For irregular spaces, split into simpler shapes and add their areas.
Measure length and width in feet, multiply them, and you have the room’s square footage. If the room isn’t a simple rectangle, divide it into sections and add them.
300 sq ft is an area, not a single dimension. For example, it could be a 15 ft × 20 ft room (15×20 = 300), or a 10 ft × 30 ft space (10×30 = 300).
Most commonly: area (ft²) = length (ft) × width (ft). Other shapes use different area formulas (triangle, circle), but the unit is still ft².
Bedroom sizes vary a lot by location and home type, but many bedrooms fall somewhere around the low hundreds of square feet. Measuring your actual room is the best way to know.