Square Footage Calculator
Calculate the square footage of any space or shape — rectangle, triangle, circle, trapezoid, or rectangular border. Convert to sq m, sq yd, and acres. Estimate project cost with price per sq ft.
📏 Square Footage Calculator
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💡 How to Calculate Square Footage
Square footage measures the area of a two-dimensional space. For a rectangle: Length × Width. For a triangle: ½ × Base × Height. For a circle: π × (Diameter/2)². For a trapezoid: ½ × (Base₁ + Base₂) × Height. All measurements must be in feet — convert inches to feet by dividing by 12 before calculating.
For irregularly shaped rooms, break the space into simple geometric shapes (rectangles, triangles), calculate each area separately, and add them together. For L-shaped rooms, split into two rectangles. For rooms with bay windows, add a triangle or trapezoid to the main rectangle.
Convert to square yards with our square yards calculator. Convert to metric with our square meters calculator. Add depth for volume with our cubic yards calculator.
Square Footage Formulas
| Shape | Formula | Variables | Example |
|---|---|---|---|
| Rectangle / Square | L × W | L = length, W = width | 12 × 10 = 120 sq ft |
| Triangle | ½ × B × H | B = base, H = height | ½ × 10 × 8 = 40 sq ft |
| Circle | π × r² | r = radius (diameter ÷ 2) | π × 5² = 78.5 sq ft |
| Trapezoid | ½ × (a + b) × h | a, b = parallel sides, h = height | ½ × (8 + 12) × 6 = 60 sq ft |
| Rectangular Border | (L × W) − (l × w) | Outer minus inner rectangle | (20 × 15) − (10 × 8) = 220 sq ft |
Step-by-Step: How to Calculate Square Footage
Step 1: Measure the Space
Use a tape measure to find the length and width of the area in feet. Measure the longest dimension of each wall. For accuracy, measure to the nearest inch and convert to feet (divide inches by 12).
Step 2: Choose the Right Formula
For rectangular rooms (most rooms), multiply length × width. For triangular sections (gables, bay windows), use ½ × base × height. For circular areas (round patios), use π × radius².
Step 3: Calculate and Add Sections
For complex rooms, split into simple shapes, calculate each section separately, and add the results. For an L-shaped room, measure two rectangles. For a room with a bay window, add the main rectangle plus a triangle or trapezoid.
Step 4: Estimate Cost (Optional)
Multiply total square footage by the price per square foot to estimate project cost. For flooring: $2–$12/sq ft (material). For painting: $1–$3/sq ft. For carpeting: $2–$8/sq ft installed.
How to Measure a Room for Square Footage
Accurate room measurement is critical for home improvement projects. Follow these tips:
- Standard rectangular rooms: Measure the longest wall (length) and the perpendicular wall (width). Multiply them together.
- L-shaped rooms: Divide into two rectangles. Measure each separately and add the areas.
- Rooms with closets: Measure the main room and closet separately. Add both if the closet will receive the same treatment (flooring, painting).
- Rooms with bay windows: Measure the main rectangle, then add the bay area (usually a triangle or trapezoid).
- Round or curved sections: Measure the diameter and use the circle formula. For half-circles (alcoves), divide the result by 2.
How to Calculate Home Square Footage
For real estate and appraisal purposes, calculating the Gross Living Area (GLA) of a home follows specific rules defined by ANSI (American National Standards Institute):
- Included: All finished, heated/cooled rooms with walls, floor, and ceiling — bedrooms, living rooms, kitchens, bathrooms, hallways, closets.
- Excluded: Garages, unfinished basements, unfinished attics, covered porches, balconies, patios, carports.
- Finished basements: Counted separately as "below-grade living area" — not included in the main GLA.
- Stairways: Counted on only one floor (typically the floor where the stairway begins).
To calculate: Measure each room individually, then add all room areas together. For multi-story homes, measure each floor separately.
Common Room Sizes in the US
| Room | Typical Size | Square Footage |
|---|---|---|
| Small Bedroom | 10 × 10 ft | 100 sq ft |
| Master Bedroom | 14 × 16 ft | 224 sq ft |
| Living Room | 12 × 18 ft | 216 sq ft |
| Kitchen | 10 × 12 ft | 120 sq ft |
| Bathroom | 5 × 8 ft | 40 sq ft |
| Master Bathroom | 8 × 10 ft | 80 sq ft |
| 1-Car Garage | 12 × 20 ft | 240 sq ft |
| 2-Car Garage | 20 × 20 ft | 400 sq ft |
| Average US Home | — | ~2,300 sq ft |
Square Footage Conversion Table
| From | To Square Feet | Formula |
|---|---|---|
| Square Inches | sq ft | sq in ÷ 144 |
| Square Yards | sq ft | sq yd × 9 |
| Square Meters | sq ft | sq m × 10.764 |
| Acres | sq ft | acres × 43,560 |
| Hectares | sq ft | hectares × 107,639 |
| Square Centimeters | sq ft | sq cm ÷ 929.03 |
Price per Square Foot Guide
Knowing the price per square foot helps estimate project costs and compare real estate values:
- Calculate price per sq ft: Total price ÷ total square footage. A $200,000 home with 2,000 sq ft = $100/sq ft.
- Estimate project cost: Square footage × price per sq ft. 300 sq ft of flooring at $5/sq ft = $1,500.
- US median home price per sq ft (2025): $150–$200/sq ft nationally. Ranges from $80/sq ft in rural areas to $500+/sq ft in NYC or San Francisco.