Square Footage Calculator

Follow these steps to calculate the square footage of any space:

1. Measure the length: Using a tape measure, laser distance measurer, or measuring wheel, determine the length of your space. For rectangular rooms, measure along the longest wall from one interior surface to the opposite. Record the measurement in your chosen unit.
2. Measure the width: Measure the dimension perpendicular to the length. For circles, enter the diameter (the distance across the full circle through its center) as the length value. For triangles, enter the base as the length and the perpendicular height as the width.
3. Select your measurement unit: Choose feet, meters, inches, or yards depending on what unit your measurements are in. The calculator handles all conversions automatically.
4. Select the shape: Choose rectangle for standard rooms, circle for round spaces, or triangle for triangular areas.

For L-shaped rooms or irregular spaces, divide the area into two or more rectangles, calculate each one separately, and add the results together. For example, an L-shaped living room can be split into two rectangles at the corner where the shape changes. Measure each rectangle independently, calculate the square footage of each, and sum them for the total area.

For the most accurate results, take measurements at multiple points along each wall, especially in older buildings where walls may not be perfectly straight. Use the average of your measurements. Always measure from the interior wall surfaces, not including baseboards or trim, for true room dimensions.

Square footage is a measurement of area expressed in square feet, representing the two-dimensional space a surface occupies. A square footage calculator determines this area by taking the dimensions of a space and applying the appropriate geometric formula based on its shape. Whether you are measuring a room, a yard, a building footprint, or a piece of land, knowing the square footage is essential for accurate planning and cost estimation.

Square footage matters across many fields and applications. In real estate, square footage is one of the primary factors determining property value. Homes are priced per square foot, and accurate measurements are required for listings, appraisals, and tax assessments. In home improvement, you need square footage to estimate materials for flooring, carpet, tile, paint, wallpaper, and other surface coverings. For landscaping, square footage determines how much sod, mulch, gravel, or seed you need for a project. Contractors and builders use square footage calculations daily for estimating project costs and ordering materials.

Measuring different shapes requires different approaches. Rectangular spaces are the simplest and most common, requiring only a length and width measurement. Circular areas like round patios, pools, or garden beds require measuring the diameter and applying the pi-based area formula. Triangular spaces need a base and height measurement. Most real-world spaces can be broken down into combinations of these basic shapes.

It is important to understand the difference between gross square footage and net square footage. Gross square footage includes the total area within the exterior walls of a building, including walls, hallways, closets, and mechanical spaces. Net square footage, also called usable or livable square footage, excludes walls, stairways, and non-habitable areas. Real estate listings typically use gross living area, but understanding both measurements helps you evaluate how much space is truly usable for furniture, activities, and daily living.

The square footage calculation uses different geometric formulas depending on the shape of the space:

• Rectangle: Area = Length × Width. This is the most common calculation for rooms, yards, and building footprints.
• Circle: Area = π × (Diameter ÷ 2)² = π × radius². The radius is half the diameter. Pi (π) is approximately 3.14159.
• Triangle: Area = (Base × Height) ÷ 2. The height must be perpendicular to the base, not the length of a side.

Unit conversion factors used by this calculator:

To convert square feet to square meters, divide by 10.764. To convert square feet to acres, divide by 43,560. These conversions are performed automatically by the calculator for every result.

Example 1 — Room Measurement for Carpet: You need to buy carpet for a master bedroom measuring 16 feet long and 14 feet wide (rectangular). Area = 16 × 14 = 224 square feet. Carpet is typically sold by the square yard, so convert: 224 ÷ 9 = 24.89 square yards. Most carpet retailers recommend adding 10 percent for waste and seams: 24.89 × 1.10 = 27.38 square yards, which you would round up to 28 square yards. In square meters, the room is 224 ÷ 10.764 = 20.81 m².

Example 2 — Flooring Project for Multiple Rooms: You are installing hardwood flooring in three rooms. Room 1 (living room): 20 ft × 18 ft = 360 sq ft. Room 2 (dining room): 14 ft × 12 ft = 168 sq ft. Room 3 (hallway): 25 ft × 4 ft = 100 sq ft. Total area = 360 + 168 + 100 = 628 sq ft. Flooring is sold in boxes covering 20 sq ft each: 628 ÷ 20 = 31.4 boxes. Add 10 percent for cuts and waste: 31.4 × 1.10 = 34.54, so you need 35 boxes. At $4.50 per square foot installed, the flooring cost is 628 × $4.50 = $2,826.

Example 3 — Irregular Shaped Yard Area: Your backyard has an L-shape that you want to sod. Break it into two rectangles: Section A is 40 ft × 30 ft = 1,200 sq ft. Section B is 20 ft × 15 ft = 300 sq ft. There is also a circular flower bed with a 10-foot diameter that will not be sodded: Area of circle = π × 5² = 78.54 sq ft. Total sodding area = 1,200 + 300 − 78.54 = 1,421.46 sq ft. In acres: 1,421.46 ÷ 43,560 = 0.0326 acres. If sod costs $0.85 per square foot installed, the total cost is 1,421.46 × $0.85 = $1,208.24.