Square footage is simply the area of a two-dimensional space, measured in square feet. It's the most common unit for floor area in the United States, used everywhere from real estate listings to flooring estimates to tax assessments.
Rectangle Formula
Area = Length × Width
Circle Formula
Area = π × radius²
Common Applications
Flooring - order the right amount of hardwood, carpet, or tile
Painting - calculate how many gallons of paint you need
Real estate - understand property size before buying or renting
Landscaping - plan grass seed, sod, mulch, or paving materials
HVAC - properly size air conditioning and heating systems
Who Is This Calculator For?
Anyone who needs to find the floor area of a space, whether for buying materials, comparing properties, or planning a project.
Homeowners buying flooring
Find the square footage before ordering hardwood, carpet, laminate, or tile.
Contractors estimating materials
Get quick area figures for any room shape to price jobs and order supplies.
Real estate buyers and renters
Verify or compare listed square footage before committing to a property.
Painters and decorators
Calculate wall or floor area to estimate paint, wallpaper, or primer needed.
Landscapers and gardeners
Measure lawn, garden bed, or patio areas for seed, mulch, or paving.
DIYers planning renovations
Work out drywall, tiling, or underlayment quantities before a weekend project.
When Should You Use It?
Before visiting a flooring store so you know how many square feet to request
When a room has an L-shape or other irregular layout that is hard to measure by eye
To convert a measurement you have in meters, inches, or yards into square feet
When comparing two rental listings with different stated square footages
Before a landscaping or concrete project to get material quantities right
How to Use the Calculator
1
Select your shape
Choose from Rectangle/Square, Circle, Triangle, or L-Shape. Pick the shape that best matches your room or space. For most rooms, Rectangle works. For hallways that turn a corner, use L-Shape.
2
Choose your input unit
Select the unit your tape measure or plans use: feet, inches, yards, meters, or centimeters. The result always converts to square feet.
3
Enter your dimensions
Type the length and width (for rectangles), the radius (for circles), the base and height (for triangles), or two section dimensions (for L-shapes). All values must be in the same unit you selected.
4
Read the total area
The result appears instantly in square feet. Below it you will also see conversions to square yards, square meters, acres, and square inches.
5
Check the material estimates
Scroll to the material estimates section in the results. These already include a 10% waste factor for flooring, tile, and drywall, and coverage rates for paint.
Example Calculations
Example 1: Rectangular living room
A living room measures 18 feet long by 14 feet wide.
Area = 18 × 14 = 252 sq ft
Flooring to order (10% waste): 252 × 1.1 = 278 sq ft
Paint, 1 coat (350 sq ft/gal): 1 gallon
12×12 tiles with 10% waste: 278 tiles
Example 2: L-shaped hallway
Section A is 20 ft × 6 ft. Section B is 10 ft × 6 ft.
Section A = 20 × 6 = 120 sq ft
Section B = 10 × 6 = 60 sq ft
Total = 120 + 60 = 180 sq ft
What Does the Result Mean?
The number you see is the floor area of the space. For context on typical room sizes:
Small bedroom100-120 sq ft
Standard bedroom130-180 sq ft
Living room200-400 sq ft
One-car garage200-250 sq ft
Average US home~2,300 sq ft
Standard parking space~162 sq ft
Common Mistakes to Avoid
!
Entering inches but leaving the unit set to feet
If your tape measure shows 144 inches and you type 144 with the unit set to feet, you will get a result 144 times too large. Always match the unit selector to how your measurement is expressed.
!
Not adding waste for materials
The raw square footage is not what you order. Flooring cuts create waste, tiles break, and you need extra for repairs. Add 10% for most flooring and 15% for wet-area tile. Our material estimates do this automatically.
!
Forgetting to subtract fixed obstacles
Cabinets, islands, closets, and built-ins sit on the floor but will not be covered by your new flooring. Measure around them rather than over them for accurate material quantities.
!
Using one measurement for an irregular room
A room that is wider at one end than the other is not a rectangle. Use L-shape mode and break it into two sections, or take multiple measurements and average them.
!
Mixing measurement units mid-project
If your architectural drawings are in meters but your tape measure is in feet, always convert everything to one unit before entering. Mixing produces compounding errors.
Frequently Asked Questions
For a rectangular room, simply multiply the length by the width. For example, a 12-foot by 15-foot bedroom is 180 square feet (12 × 15 = 180). For irregular rooms, break them into rectangles, calculate each area, and add them together.
Standard area formulas: Rectangle = L × W; Circle = π × r²; Triangle = 0.5 × base × height. These are universally accepted mathematical definitions.
J
James Ortega
Licensed General Contractor, 18 years in residential construction and renovation
James reviewed the shape formulas, unit conversion factors, material waste estimates, and practical guidance on this page. He has managed flooring, tiling, and drywall projects across hundreds of residential builds.
Reviewed: March 2025Last updated: April 2025
Quick Reference
Unit
= Sq Ft
1 sq yard
9 sq ft
1 sq meter
10.76 sq ft
1 acre
43,560 sq ft
1 sq inch
0.0069 sq ft
1 sq mile
27.9M sq ft
Pro Tip
Always add 10% overage for flooring materials to account for cuts, waste, and future repairs. For tile in wet areas, use 15% overage.