π Siding Calculator
Calculate siding squares, pieces, and cost for your home exterior.
Siding Needed (incl. waste)
How to Use This Calculator
Add each wall separately for the most accurate result. Enter the wall width and height, then add doors and windows to subtract their area from the total. The calculator converts net wall area into squares (100 sq ft per square), which is how siding is sold and priced.
Measure each wall individually. Width times height gives the wall area. Click "Add Wall" for each additional wall face on your house.
Count your doors and windows. The calculator uses 20 sq ft per door and 15 sq ft per window as standard deductions. Adjust mentally for unusually large openings.
Do not forget gable ends. The triangular area at the top of a gable wall is calculated as 0.5 times the base width times the height from the eave to the peak. Add it as a separate wall entry.
Set your waste percentage. Simple rectangular walls: 10%. Homes with lots of angles, dormers, and trim cuts: 15 to 20%.
Siding Material Formula
One square equals 100 square feet of coverage. Most vinyl siding boxes contain 2 squares (200 sq ft). Fiber cement lap siding is typically sold by the piece. Divide your total square footage by the coverage per piece to find piece count.
Example Projects
Tips for Your Project
Order all your siding from the same production lot when possible. Vinyl siding color can vary between production runs, and mismatched sections are obvious once the sun hits them at a raking angle. If you cannot get everything from one lot, plan the seam at an inconspicuous location like a back corner. Keep one extra box as a repair supply.
Do not forget to budget for trim and accessories. J-channel frames every window and door. F-channel or utility trim runs along the soffit. Corner posts go on every outside corner, and inside corners need their own trim. Add up all your linear footage for these items separately since they are sold by the piece or stick, not by the square.
Frequently Asked Questions
What is a square of siding?
Like roofing, siding is measured in squares: 1 square = 100 sq ft of coverage. All siding is priced and ordered by the square.
How do I measure for siding?
Calculate total wall area (all sides), subtract doors and windows, add 10β15% waste. For gable ends, calculate the triangular area (0.5 Γ base Γ height).
How much waste should I add?
Simple rectangular home: 10%. Home with dormers, angles, special trim: 15β20%. Always order extra β dye lots can vary between orders.
What is the coverage of vinyl siding?
Vinyl siding comes in squares. A single 12" exposed-face panel 12 ft long covers 12 sq ft. Boxes typically contain 2 squares (200 sq ft).
Can I install siding over old siding?
Yes for vinyl, but check for rot/damage first. Adding new siding over old changes window depths and requires extended trim pieces. It adds insulation value but may retain moisture.