Square Footage Calculator
Calculate area in square feet for rooms, floors, walls, and irregular spaces to plan material purchases and project costs.
Calculate Your Square Footage Calculator
The Square Footage Calculator helps you determine the area of spaces in square feet, which is essential for construction, renovation, decorating, and real estate applications. Whether you're planning to install flooring, paint walls, purchase a home, or estimate material costs, knowing the square footage is the first step.
How Square Footage is Calculated
The formula varies depending on the shape of the area:
- Rectangle/Square: Area = Length × Width
- Circle: Area = π × r² (where r is the radius)
- Triangle: Area = ½ × Base × Height
- Trapezoid: Area = ½ × (Base₁ + Base₂) × Height
- Irregular spaces: Divide into regular shapes, calculate each separately, then add them together
Common Applications for Square Footage Calculations
| Application | How Square Footage is Used | Tips |
|---|---|---|
| Flooring | Determine material quantities and installation costs | Add 5-10% extra for waste and cutting |
| Painting | Calculate paint quantities | Subtract window and door areas; add for second coat |
| Real Estate | List property size, determine price per square foot | Different standards exist for measuring residential vs. commercial space |
| Landscaping | Estimate sod, soil, mulch, or gravel needs | Use irregular shape calculations for curved garden beds |
| HVAC | Size heating and cooling systems | Consider ceiling height and insulation values |
| Construction | Plan building layouts, estimate material needs | Always verify measurements on-site before ordering materials |
Tips for Accurate Square Footage Measurements
- Measure each dimension twice to verify accuracy
- For irregular rooms, break the space into regular shapes
- Include closets and built-in features for total room size
- Exclude the space occupied by staircases when calculating floor area
- For walls, calculate the perimeter of the room times the ceiling height
- Subtract windows and doors from wall measurements for painting calculations
- For sloped ceilings, use the average height measurement
- Keep all measurements in the same unit for consistency
Common Conversion Factors
- 1 square foot = 144 square inches
- 1 square foot = 0.093 square meters
- 1 square foot = 0.111 square yards
- 1 square meter = 10.764 square feet
- 1 square yard = 9 square feet
- 1 acre = 43,560 square feet
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Frequently Asked Questions
To calculate the square footage of a rectangular room, measure the length and width of the room in feet and multiply these numbers together. For example, a room that is 12 feet long and 10 feet wide has 12 × 10 = 120 square feet. For irregularly shaped rooms, divide the space into rectangles, calculate each separately, and add them together.
For flooring calculations, measure the length and width of each room, multiply to get the square footage, and add all rooms together. For irregular spaces, break them down into regular shapes. It's recommended to add 5-10% extra to account for waste, cuts, and mistakes. If your flooring comes in boxes, divide the total square footage needed by the square footage per box to determine how many boxes to purchase.
To calculate wall square footage for painting:
- Measure the perimeter of the room (add up all wall lengths)
- Multiply by the ceiling height to get the total wall area
- Subtract the area of doors (typically 20 sq ft each) and windows (typically 15 sq ft each)
- The result is your paintable wall square footage
In real estate and construction:
- Gross square footage includes the entire area within the exterior walls, including all rooms, closets, hallways, stairs, and wall thicknesses.
- Net square footage refers only to the usable or "livable" space, excluding areas such as wall thickness, mechanical rooms, and sometimes hallways or stairwells.
To calculate the square footage of a multi-floor house:
- Calculate the square footage of each floor separately
- Add the square footage of all floors together
For a 12×15 foot room, you would need 12 × 15 = 180 square feet of carpet. However, carpet is typically sold in rolls with standard widths (usually 12 feet), and you need to purchase enough to cover the entire area with minimal seams. For this room size, you'd need a piece 15 feet long from a 12-foot-wide roll. Additionally, you should add 10% extra for waste and pattern matching, bringing the total to about 198 square feet. Be sure to consult with your flooring installer, as they may have specific recommendations based on the carpet you select and the room layout.
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