What is a "Square" of siding?

A "Square" is a standard unit of measurement in the siding and roofing industries. It represents an area of 100 square feet.

How much siding do I need for a 2,000 sq ft house?

It depends on the exterior wall area, not the interior living space. Usually, a 2,000 sq ft home has between 20 and 25 squares of siding.

Should I remove old siding before installing new siding?

Yes. While "siding-over-siding" is possible, it hides potential rot and makes it difficult to install proper flashing and house wrap.

Siding Calculator - Free Professional Tool | HomeCalc Pro

Introduction to Siding Calculator

Plan your project with precision using our 2026 standardized calculator.

How to Use the Siding Calculator

Step 1: Measure Rectangular Wall Sections: Measure the length and height of each rectangular wall section of your house. Calculate the square footage (Length x Height) for each and sum them.
Step 2: Calculate Gable Triangle Area: For triangular gables, measure the width (base) and the height (from the eaves to the peak). Multiply (Base x Height) / 2 to find the area.
Step 3: Subtract Large Openings (Optional): Subtract the square footage of large garage doors or sliding glass walls. For standard windows and doors, professionals typically do not subtract them to allow for cutting waste.
Step 4: Select Siding Type: Choose your material (Vinyl, Fiber Cement, Wood). This helps determine the waste factor, as some materials break more easily than others.
Step 5: Review Total Squares: The tool provides the total square footage and the number of "Squares" you need to order from the supplier.

Understanding Siding

The key to a professional siding job is Layout and Overlap. Siding panels are designed to overlap both vertically and horizontally to shed water effectively. When calculating your material, you must account for this "lost" area. Our calculator uses the standard 100 sq ft "Square" measurement, which accounts for the manufacturer's intended overlap. However, the most common mistake is failing to account for Trim and Accessories. Siding requires J-channels, starter strips, corner posts, and soffit panels to create a finished look. These are sold by the linear foot, not the square. While our tool focuses on the main wall coverage, we recommend adding 10-15% more material for projects with complex architecture or many windows to ensure you have enough pieces for the smaller "fill" sections.

Material choice significantly impacts both cost and installation difficulty. Vinyl Siding is the most popular due to its low cost and ease of installation; it expands and contracts significantly, so it must be "hung" loosely on the nails. Fiber Cement Siding is much heavier and more durable, offering superior fire resistance and a look that mimics real wood, but it requires specialized blades and two-person handling. Natural Wood Siding offers the highest aesthetic value but requires regular painting or staining every 3-5 years to prevent rot. Our calculator helps you get the quantities right for all three, but remember that your Underlayment (House Wrap) is equally important. Installing a high-quality moisture barrier behind your siding is the only way to prevent long-term mold and structural damage to your home's sheathing. Always follow the manufacturer's specific "Nailing Schedule" to ensure your warranty remains valid.

Formula & Calculation Method

Total area is divided by 100 to find the number of "squares." A 10% waste factor is applied to the final count.

Squares = (Total Wall Area + Total Gable Area) / 100 * 1.10

Example Calculation:

A house with 2,500 sq ft of wall area needs (2,500 / 100) * 1.1 = 27.5 Squares (order 28).

Tips for Accurate Results

1Measure your house during a "cloudy" day to avoid the glare from the sun, which can make reading a tape measure difficult.
2Always order 10% more material than you think you need; color lots for siding can change, and a second order might not match perfectly.
3Check your local building code for "Fire Rating" requirements if your home is close to a property line.
4Use "Color-Matched" caulk for all joints where siding meets trim for a truly professional finish.
5Install siding during mild weather; vinyl becomes brittle in extreme cold and expands too much in extreme heat.

What Is a Siding Calculator?

A siding calculator is a tool that helps you estimate the total amount of siding material required for your home's exterior. It also provides a budget estimate for the installed cost based on the material type you choose. The key unit of measurement for siding is the "square," which is equal to 100 square feet.

How to Use This Calculator

Enter your home's total perimeter and average wall height.
If you have gables, enter their dimensions and quantity.
Input the total area of windows and doors to be excluded.
Choose your desired siding material type.
Click "Calculate" to get your material estimate and budget range.

Understanding Your Siding Estimate

Total Siding Required (sq ft): The net square footage of your walls and gables that needs to be covered, including a waste factor.
Siding Squares: The total area converted into the industry standard unit. One square = 100 sq ft. Siding is sold by the square.
Estimated Boxes: An approximation of how many boxes of siding you'll need, as it's often sold in 2-square boxes.
Estimated Installed Cost: A budget range for the project, including both materials and professional labor.

Frequently Asked Questions

Key Facts About Siding

•Siding is sold by the "Square," which equals 100 square feet.
•Fiber cement siding offers superior fire resistance compared to vinyl.
•House wrap is the critical moisture barrier behind your siding.
•Vinyl siding must be hung loosely to allow for thermal expansion.
•Adding 10-15% waste is standard for houses with many gables or windows.

Siding Calculator