Square Footage Calculator
Quickly find your Area of a space with our free Square Footage Calculator. Simple, fast, and accurate.
Dimensions
Area & cost
What is a Square Footage Calculator?
A Square Footage Calculator computes the area of a space in square feet. It supports rectangles and circles, multiple measurement units (feet, metres, inches, yards), and optional price-per-square-foot calculations for estimating material costs.
How to calculate square footage manually (the formula)
For a rectangle: Area = Length × Width. For a circle: Area = π × r², where r is the radius (half the diameter). Measure in feet for direct square footage, or convert from other units using standard conversion factors.
Example calculation
A room measuring 12 ft by 15 ft: 12 × 15 = 180 sq ft. For an 18 by 18 inch tile (1.5 ft by 1.5 ft): 1.5 × 1.5 = 2.25 sq ft per tile. 180 ÷ 2.25 = 80 tiles needed. For a circular area with a 10 ft diameter: radius = 5 ft, area = π × 5² = 78.54 sq ft.
Common mistakes
- Mixing measurement units — Always use the same unit (e.g., all feet or all inches). Converting mid-calculation leads to errors.
- Forgetting to convert inches to feet — Divide inches by 12 to get feet. For example, 18 inches = 18 ÷ 12 = 1.5 ft.
- Using diameter instead of radius for circles — The formula uses radius (half the diameter). Using the full diameter gives an area four times larger than correct.
Frequently asked questions
How do you calculate square footage of a room?
Multiply the length by the width: Area = Length × Width.
How do I calculate square feet for an 18x18 area?
Multiply 18 by 18: 18 × 18 = 324 square feet.
What is the formula for square footage?
Area = Length × Width (for rectangles) or π × r² (for circles).
How do you convert square feet to square meters?
Multiply by 0.0929: 1 sq ft = 0.0929 m².
Is this free?
Yes, completely free.
Does it work on mobile?
Yes, works on any device.