Square Footage Calculator
Calculate the area of a room or any regular shape, add rooms into a running total, and convert the result into square yards, square meters and a material cost.
How to use this calculator
- Pick the shape that matches the space. Most rooms are rectangles; bay windows are trapezoids; a round patio is a circle measured across its widest point.
- Break odd rooms into pieces. An L-shaped living room is two rectangles. Calculate the first, press Add this area to the running total, then change the numbers and add the second. The total updates as you go.
- Mix units freely. Each field has its own unit, so 12 ft 6 in can be entered as 12.5 ft, and a plan drawn in meters needs no conversion on your part.
- Add an allowance if you are buying material. Flooring and tile need about 10% for cuts; paint and drywall do not, since you are measuring surfaces you will cover completely.
The formula
| Shape | Area |
|---|---|
| Rectangle or square | length × width |
| Circle | π × (diameter ÷ 2)² |
| Triangle | ½ × base × height |
| Trapezoid | ½ × (side A + side B) × distance between them |
Every input is converted to feet first, so the result is always in square feet. The unit conversions used are exact:
| From | To square feet |
|---|---|
| 1 square inch | ÷ 144 |
| 1 square yard | × 9 |
| 1 square meter | × 10.7639 |
| 1 acre | × 43,560 |
Worked example
An L-shaped room: the main part is 16 × 12 ft, with a 6 × 8 ft alcove. Buying flooring at $3.40 per sq ft with a 10% allowance:
- Main area: 16 × 12 = 192 sq ft → add to total
- Alcove: 6 × 8 = 48 sq ft → add to total
- Total: 240 sq ft (26.7 sq yd, 22.3 m²)
- With 10%: 240 × 1.10 = 264 sq ft to buy
- Cost: 264 × $3.40 = $897.60
Measuring the L as one 16 × 20 ft rectangle would have given 320 sq ft — an $270 error in the wrong direction.
Common conversions
| Square feet | Square yards | Square meters |
|---|---|---|
| 100 | 11.1 | 9.3 |
| 200 | 22.2 | 18.6 |
| 500 | 55.6 | 46.5 |
| 1,000 | 111.1 | 92.9 |
| 1,500 | 166.7 | 139.4 |
Frequently asked questions
How do I calculate square footage of a room?
Measure the length and the width in feet and multiply them. A room 12 feet by 10 feet is 120 square feet. If the room is not a rectangle, split it into rectangles, triangles or circles, work out each one, and add the results together.
How do I find the square footage of an L-shaped room?
Divide the L into two rectangles along a straight line, measure each one separately, and add the two areas. Treating the whole L as a single rectangle counts the missing corner and can overstate the area by a third.
How many square feet are in a square yard?
Nine. A square yard is 3 feet by 3 feet. To convert square feet to square yards divide by 9, and to go the other way multiply by 9. Carpet is often priced per square yard while the room is measured in square feet, which is where mistakes creep in.
How many square feet are in a square meter?
About 10.764. To convert square meters to square feet multiply by 10.764; to convert square feet to square meters multiply by 0.0929.
Should I include closets and hallways?
For flooring, yes, if you are flooring them — measure and add every space that gets material. For a published house measurement, follow the standard your appraiser uses, which generally counts finished, heated space measured to the exterior walls.
Guides
- How to Measure the Square Footage of a Room
- Square Feet, Square Yards and Square Meters: Converting Without Errors
- How Much Flooring Do I Need?
- Linear Feet vs Square Feet: Which One Are You Buying?
- How to Calculate the Square Footage of a House