Square Footage Calculator
Calculate the area of any room or space in square feet. Choose from rectangular, triangular, and circular shapes with automatic unit conversions.
About This Calculator
The Square Footage Calculator determines the area of a space in square feet, square meters, and acres. It supports three common shapes: rectangle (length times width), triangle (half of base times height), and circle (pi times radius squared). Contractors, homeowners, and renters use square footage calculations for flooring estimates, paint coverage, furniture planning, and rental listings. All conversions happen automatically so you never have to look up conversion factors.
How to Use
- Enter your values in the input fields above
- Click the calculate button to see results
- Review your results displayed below the inputs
- Use the reset button to clear all fields and start over
The Formula
How the calculation works under the hood
Rectangle area
Multiply the two side lengths together.
Triangle area
Half the base times the perpendicular height.
Circle area
Pi (3.14159) times the radius squared.
Worked Example
Step-by-step walkthrough with real numbers
“A rectangular living room measures 15 feet long and 12 feet wide.”
- 1Length = 15 ft, Width = 12 ft.
- 2Area = 15 x 12 = 180 sq ft.
- 3In square meters: 180 x 0.0929 = 16.72 sq m.
- 4In acres: 180 / 43,560 = 0.0041 acres.
The room is 180 square feet (16.72 square meters).
⚠️Common Mistakes
- ✕Measuring in inches but forgetting to convert to feet before multiplying (divide inches by 12 first).
- ✕Ignoring alcoves, closets, or bay windows when measuring irregularly shaped rooms.
- ✕Confusing linear feet (a length) with square feet (an area).
💡Pro Tips
- ✓For L-shaped rooms, split into two rectangles, calculate each, and add the results.
- ✓Most flooring and paint coverage estimates are listed per square foot, so this number directly feeds into material calculators.
- ✓When listing a rental or sale, measure to the nearest 0.5 foot for accuracy.
Related Guides
Go deeper with these in-depth articles
How to Calculate Square Footage for Any Room or Space
Measure and calculate the area of any room or space — rectangles, triangles, circles, and irregular shapes — with simple formulas and examples.
Read guide →How to Calculate Square Footage for Flooring, Paint, and Tiling
Measure any room accurately for flooring, paint, or tile. Covers rectangular and odd-shaped rooms, waste allowances, and the mistakes that lead to overbuying.
Read guide →Frequently Asked Questions
How do I calculate square footage of a rectangular room?
Multiply the length by the width in feet. For example, a 12 ft x 15 ft room is 180 square feet.
Can I calculate irregular shapes?
Break the space into smaller rectangles, triangles, or circles, calculate each area separately, and add them together.
How do I convert square feet to square meters?
Multiply square feet by 0.0929. The calculator shows both square feet and square meters automatically.
What is an acre in square feet?
One acre equals 43,560 square feet. The calculator shows the acre equivalent for any area you compute.
How do I measure an L-shaped room?
Divide the L-shape into two rectangles, calculate each one separately, then add the results together for the total area.
Is this calculator free to use?
Yes! All calculators on Get Precision Calculator are completely free with no limitations or sign-up required.
Is my data saved or tracked?
No. All calculations are performed locally in your web browser. Get Precision Calculator does not store, collect, or track your calculation data.
Related Calculators
You might also be interested in these
Basic Calculator
Perform basic arithmetic operations like addition, subtraction, multiplication, and division with decimal support.
Percentage Calculator
Calculate percentages, percentage increase/decrease, and find what percentage one number is of another.
Unit Converter
Convert between units of length, weight, temperature, volume, area, and speed instantly.