Square Footage Calculator
Calculate the square footage of any room, house or surface — rectangles, circles, triangles, L-shapes and more — in square feet, inches and meters.
A room that is 10 ft by 12 ft has 120 square feet.
How to Use This Square Footage Calculator
- Choose the shape of the area: rectangle, square, circle, triangle, trapezoid or L-shape.
- Enter the measurements in feet (or inches — the calculator converts automatically).
- For L-shaped or irregular rooms, measure each section separately and add them.
- Read the result in square feet, square inches and square meters.
The Formulas
Square footage is simple geometry. Multiply length × width for rectangles and squares, use πr² for circles, half base × height for triangles, and the average of the parallel sides × height for trapezoids. For L-shaped rooms, split the space into rectangles and add the results.
A = L × W Rectangle / square (feet × feet = square feet) A = π × r² Circle (r = radius) A = ½ × b × h Triangle A = ½ × (b1 + b2) × h Trapezoid 1 ft² = 144 in² · 1 yd² = 9 ft² Conversions Worked Example: 12×12 Room
A bedroom that is 12 ft by 12 ft: A = 12 × 12 = 144 square feet. If it has a 4×6 ft closet, add 24 more square feet for a total of 168 sq ft.
Square Footage of Common Room Sizes
| Room | Size | Square feet |
|---|---|---|
| Small bedroom | 10 × 10 ft | 100 |
| Bedroom | 10 × 12 ft | 120 |
| Bedroom | 12 × 12 ft | 144 |
| Large bedroom | 12 × 14 ft | 168 |
| Living room | 14 × 16 ft | 224 |
| Garage | 20 × 20 ft | 400 |
Length × width, in feet.
How to Measure an Irregular Room
For L-shaped or irregular rooms, divide the space into rectangles, measure each one and add the results. Measure to the nearest inch — rounding too aggressively can change your flooring or paint order by 5% or more. When buying materials, it is always safer to add a small waste allowance on top of the exact area.
Quick Tips
- Measure in feet and inches, then convert: 12 inches = 1 foot.
- An acre is 43,560 square feet; a square meter is 10.764 square feet.
- For paint or flooring, add 10% waste on top of the exact area.
Frequently Asked Questions
How do I calculate the square footage of a room?
Measure the length and width in feet and multiply them. A room 10 ft by 12 ft is 120 square feet (10 × 12 = 120).
How many square feet is a 12×12 room?
144 square feet (12 × 12 = 144).
How do I measure an L-shaped room?
Split it into two rectangles, calculate each one, and add the results together.
How do I convert square feet to square meters?
Divide the square footage by 10.764. 200 sq ft ÷ 10.764 ≈ 18.6 square meters.
How many square feet are in an acre?
43,560 square feet.