Quick answer: Multiply the length by the width in feet. A 12 × 15 ft room is 180 sq ft. For other shapes, split the area into rectangles, triangles and circles, calculate each one and add them together.
Square Footage Formulas
| Shape | Formula | Example |
|---|---|---|
| Rectangle | Length × Width | 12 × 15 ft = 180 sq ft |
| Triangle | ½ × Base × Height | ½ × 10 × 8 = 40 sq ft |
| Circle | 3.1416 × Radius² | 10 ft across: 3.1416 × 5² = 78.5 sq ft |
| Trapezoid | (Side a + Side b) ÷ 2 × Height | (6 + 10) ÷ 2 × 8 = 64 sq ft |
How to Measure a Room
- Measure the longest wall from corner to corner and the wall at right angles to it.
- Measure in feet and inches, then convert inches to feet (divide by 12). 12 ft 6 in = 12.5 ft.
- Multiply length by width.
- Round up slightly when you order materials.
L-Shaped and Irregular Rooms
Split an L-shaped room into two rectangles. Example: a 20 × 12 ft section plus a 10 × 8 ft section = 240 + 80 = 320 sq ft. For a bay window or angled wall, add a triangle or trapezoid.
Skip the math: pick the shape, enter your measurements in feet or meters and get sq ft, sq yd, m² and acres. Open the free Square Footage Calculator →
Square Footage of a House
Measure the outside of each floor, multiply length by width for each rectangular section and add them. Listings usually count finished, heated living space only, not garages, unfinished basements or porches.
Converting Units
| Unit | Equals |
|---|---|
| 1 sq ft | 144 sq in = 0.0929 m² |
| 1 sq yd | 9 sq ft |
| 1 m² | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
What You Can Do With Square Footage
- Order flooring with the flooring calculator.
- Buy carpet by the square yard with the carpet calculator.
- Size paint with the paint calculator.
- Price sod or seed for a lawn with the sod calculator.
Square Footage of Common Room Sizes
| Room size | Square feet | Square meters |
|---|---|---|
| 10 × 10 ft | 100 | 9.3 |
| 10 × 12 ft | 120 | 11.1 |
| 12 × 12 ft | 144 | 13.4 |
| 12 × 14 ft | 168 | 15.6 |
| 12 × 16 ft | 192 | 17.8 |
| 14 × 16 ft | 224 | 20.8 |
| 16 × 20 ft | 320 | 29.7 |
| 20 × 20 ft | 400 | 37.2 |
Measuring Walls Instead of Floors
For paint, wallpaper and drywall, you need wall area: perimeter × wall height, minus doors and windows. A 12 × 14 ft room with 8 ft walls has 52 × 8 = 416 sq ft of wall. Our paint calculator and drywall calculator handle this for you.
Measuring a Yard or Lot
Measure the property in sections, using a long tape or a measuring wheel. Subtract the house, driveway and patios to find the lawn area for seed, sod or fertilizer. One acre is 43,560 sq ft, so a quarter-acre lot is about 10,890 sq ft.
Tips for Accurate Measurements
- Measure twice and write measurements down as you go.
- Measure at floor level, past baseboards, for flooring.
- Use a laser measure for long rooms.
- Add 5–15% waste for flooring and tile depending on the pattern.
Frequently Asked Questions
How do I calculate square feet from inches?
Multiply length by width in inches and divide by 144. Or convert each measurement to feet first.
How many square feet is a 10×12 room?
120 square feet.
How do I convert square feet to square meters?
Multiply by 0.0929 or divide by 10.764.
Do closets count in square footage?
Closets are included in a home’s finished square footage and in flooring orders if you will cover them.
How many square feet is a 2 car garage?
A typical two-car garage is about 20 × 20 ft to 24 × 24 ft, or 400–576 sq ft.
Related Guides
- How to Measure a Room for Flooring (Step-by-Step)
- How Many Tiles Do I Need for a Bathroom Floor or Shower?
- What Size Wire Do I Need? Amps, Distance and Voltage Drop
Try the free Square Footage Calculator or browse all home improvement calculators.