Gable End Siding Calculator

How to Calculate Siding for a Gable End

Gable ends are the triangular portions of a wall between the edges of intersecting roof pitches. Because of the steep angles and diagonal cuts required, calculating the exact amount of siding material can be tricky. This tool helps you estimate the square footage and total material needed for any standard gable.

Step 1: Measuring the Dimensions

To use the calculator, you need two primary measurements:

• Base Width: Measure the horizontal distance along the bottom of the gable (where it meets the rectangular wall below).
• Gable Height: Measure the vertical distance from the center of the base line straight up to the peak of the roof.

Step 2: The Triangle Formula

The standard geometric formula for the area of a triangle is (Base × Height) / 2. If your gable has a base of 20 feet and a height of 10 feet, the net area is 100 square feet.

Step 3: Accounting for Waste

Unlike flat rectangular walls, gables result in significant scrap material due to the diagonal cuts required to follow the roofline. Experts recommend adding a 15% waste factor for gables, compared to the standard 5-10% used for the rest of the house.

Siding "Squares" Explained

In the construction industry, siding is often sold by the "square." One square is equal to 100 square feet of coverage. Our calculator automatically converts your total square footage into squares to make ordering from suppliers easier.

Pro Tip: If you are using vertical siding (like board and batten) for your gables, the waste factor may be slightly higher than horizontal lap siding because of how the panels align with the peak.

function calculateGableSiding() { var width = parseFloat(document.getElementById('baseWidth').value); var height = parseFloat(document.getElementById('gableHeight').value); var wastePercent = parseFloat(document.getElementById('wasteFactor').value); var costPerSq = parseFloat(document.getElementById('costPerSqFt').value); if (isNaN(width) || isNaN(height) || width <= 0 || height 0) { totalCost = totalArea * costPerSq; } // Display Results document.getElementById('netArea').innerText = netArea.toFixed(2) + " sq ft"; document.getElementById('totalArea').innerText = totalArea.toFixed(2) + " sq ft"; document.getElementById('squaresNeeded').innerText = squares.toFixed(2); if (totalCost > 0) { document.getElementById('totalCost').innerText = "$" + totalCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); } else { document.getElementById('totalCost').innerText = "N/A"; } document.getElementById('results').style.display = "block"; }