Square Footage Calculator
Multiply length × width in feet. A 12 × 15 ft room is 180 square feet, which is 20 square yards. For an odd shape, split it into rectangles, triangles and circles and add them up.
Updated October 19, 2026 · How we calculate
Worked example
An L-shaped room: a 12 × 15 ft main area with a 6 × 8 ft nook.
- Main area: 12 × 15 = 180 square feet
- Nook: 6 × 8 = 48 square feet
- Total: 180 + 48 = 228 square feet
- In square yards: 228 ÷ 9 = 25.33
How to choose and how deep
How to measure square footage
- Measure the length and width, wall to wall or edge to edge, in feet.
- If a measurement is in inches, divide it by 12 to get feet (6 ft 6 in = 6.5 ft).
- Multiply length × width.
- For L-shapes and odd rooms, split the space into rectangles, measure each, and add them up.
Circles and triangles
A circle is 3.1416 × the radius × the radius. A 10 ft circle has a 5 ft radius, so it is 78.5 square feet.
A triangle is the base × the height ÷ 2, with the height measured square to the base.
Buying materials
Flooring, tile and sod need extra for cuts. Use the extras step to add a percentage, and check the maker's advice for how much.
Quick reference
| Unit | In square feet |
|---|---|
| 1 square inch | 1/144 (0.00694) |
| 1 square yard | 9 |
| 1 square meter | 10.7639 |
| 1 acre | 43,560 |
Source: NIST Handbook 44 (2024), Appendix C
Questions people ask
How do you calculate square footage?
Measure the length and width in feet and multiply them. A 12 × 15 ft room is 180 square feet.
How many square feet are in a square yard?
Nine. A square yard is 3 feet by 3 feet.
How many square feet are in an acre?
43,560 square feet.
Source: NIST Handbook 44 (2024), Appendix C
How do you convert square inches to square feet?
Divide by 144, because a square foot is 12 inches by 12 inches.
How many square feet are in a square meter?
About 10.764. One square foot is exactly 0.09290304 square meters.
Source: NIST Handbook 44 (2024), Appendix C