Square Footage Calculator
Calculate the square footage of rooms, houses, and spaces. Perfect for flooring, painting, and real estate measurements.
Room Dimensions
Area Results
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sq ft
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m²
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yd²
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acres
💡 Pro Tip: Always add 10% extra to your square footage when buying materials like flooring or paint to account for cuts and waste.
How to Calculate Square Footage
Square footage is the area of a space measured in square feet. It's essential for real estate, construction, flooring, painting, and landscaping projects.
Formulas for Different Shapes
Rectangle or Square
Area = Length × Width
Example: 12 ft × 10 ft = 120 sq ft
Example: 12 ft × 10 ft = 120 sq ft
Triangle
Area = (Base × Height) / 2
Example: (10 ft × 8 ft) / 2 = 40 sq ft
Example: (10 ft × 8 ft) / 2 = 40 sq ft
Circle
Area = π × r²
Example: 3.14159 × 5² = 78.54 sq ft
Example: 3.14159 × 5² = 78.54 sq ft
Trapezoid
Area = ((a + b) / 2) × h
Where a and b are the parallel sides, h is the height
Where a and b are the parallel sides, h is the height
Common Room Sizes
| Room Type | Average Size | Square Footage |
|---|---|---|
| Bedroom (Small) | 10' × 10' | 100 sq ft |
| Bedroom (Medium) | 12' × 12' | 144 sq ft |
| Bedroom (Large/Master) | 14' × 16' | 224 sq ft |
| Living Room | 16' × 20' | 320 sq ft |
| Kitchen | 10' × 12' | 120 sq ft |
| Bathroom | 5' × 8' | 40 sq ft |
| Garage (1-car) | 12' × 20' | 240 sq ft |
| Garage (2-car) | 20' × 20' | 400 sq ft |
How to Measure a Room
- Use a tape measure: A 25-foot tape measure works for most rooms.
- Measure length: Measure the longest wall from corner to corner.
- Measure width: Measure the perpendicular wall.
- Record measurements: Write down feet and inches.
- Convert inches to decimals: 6 inches = 0.5 feet, 3 inches = 0.25 feet.
- Multiply: Length × Width = Square Footage.
Adding 10% for Waste
When buying materials, always add 10% extra to account for cuts, mistakes, and waste:
Materials Needed = Square Footage × 1.10
Example: 120 sq ft × 1.10 = 132 sq ft of materials needed
Example: 120 sq ft × 1.10 = 132 sq ft of materials needed
⚠️ Important: For irregularly shaped rooms, break the space into smaller rectangles, calculate each separately, then add them together.
References
- Home Depot. "How to Measure Square Footage." 2026.
- This Old House. "Measuring Rooms." 2026.