Calculate area in square feet for any shape — rectangles, circles, and triangles. Perfect for flooring, painting, and construction projects.
Select a shape and enter dimensions to calculate the area.
A square footage calculator computes the area of a space in square feet (sq ft or ft²). Whether you're planning a home renovation, ordering flooring materials, or estimating paint coverage, knowing the exact square footage is essential for budgeting and purchasing the right quantity of materials. According to the National Association of Home Builders (NAHB), the average new American home is approximately 2,500 square feet.
Square footage measurements are the standard in the United States real estate market and construction industry. They directly impact property valuations, rental pricing, and material costs. For volume-based projects requiring depth measurements, check our Cubic Yards Calculator.
Example: A room measures 12 feet by 15 feet
Area = 12 × 15 = 180 square feet
Example: A circular patio with a 10-foot diameter (radius = 5 ft)
Area = 3.14159 × 5² = 3.14159 × 25 = 78.54 square feet
Example: A triangular garden bed with base 8 ft and height 6 ft
Area = 0.5 × 8 × 6 = 24 square feet
When working with different measurement units, use these conversion factors (sourced from NIST — National Institute of Standards and Technology):
Our Unit Converter can help with additional conversions between measurement systems.
For L-shaped or irregular rooms, break the space into rectangles, calculate each area separately, then add them together. For very complex shapes, Math is Fun's area guide recommends dividing into simple geometric shapes (rectangles, triangles, semicircles) and summing the areas.
One acre contains 43,560 square feet. To visualize this, an acre is approximately 90% of an American football field (which is 48,000 sq ft including end zones).
Measure the width and height of each wall, multiply them together, then add all wall areas. Subtract the area of doors and windows for painting estimates.
Linear feet measures length in a straight line (one dimension), while square feet measures area (two dimensions: length × width). You need both dimensions for square footage.
A 12×12 room is 144 square feet. With the recommended 10% waste factor, you'd need about 158 sq ft of flooring material.
Square footage is a measure of area: how much two-dimensional surface a space covers, expressed in square feet. It is the standard unit for pricing flooring, paint, tiling, turf and real estate in the United States and several other markets. A square footage calculator works out the area of a space and, just as importantly, how much material to order once cutting waste is taken into account.
Step 1: Calculate the main rectangle
Step 2: Calculate the alcove
Step 3: Add them together
Step 4: Add 10 percent waste for straight-lay flooring
The floor area is 328 sq ft; order 361 sq ft to allow for cuts
| Situation | Add | Why |
|---|---|---|
| Straight-lay flooring, simple room | 10% | Standard cutting waste |
| Diagonal or herringbone | 15% | Angled cuts create larger offcuts |
| Rooms with many angles | 15% to 20% | More cuts, more waste |
| Large-format tile | 15% | Offcuts are less reusable |
| Patterned material | 15% to 20% | Pattern matching wastes material |
Flooring and tile are produced in batches, and colour varies slightly between them. Running short and reordering often means a visible mismatch, because the new batch will not match the old exactly. Ordering the full amount including waste in a single order avoids this, and leftover material is worth keeping for future repairs.
| From | To | Multiply By |
|---|---|---|
| Square feet | Square metres | 0.0929 |
| Square metres | Square feet | 10.7639 |
| Square feet | Square yards | 0.1111 |
| Square yards | Square feet | 9 |
| Acres | Square feet | 43,560 |
One foot is 0.3048 metres, but one square foot is 0.0929 square metres, not 0.3048. Area scales with the square of the linear factor. Using the linear conversion on an area figure is a common and expensive mistake when ordering materials from a supplier using different units.
Paint is calculated on wall area rather than floor area, and the arithmetic differs. Multiply the room perimeter by the ceiling height, then subtract windows and doors.
About 417 sq ft to cover, roughly one gallon per coat at typical coverage rates
This calculator is for general estimation. For construction, property listings or contractual purposes, follow the measurement standard applicable in your jurisdiction and confirm quantities with your supplier or contractor.