function calculateBorder() {
var totalFeet = parseFloat(document.getElementById("totalPerimeter").value);
var unitInches = parseFloat(document.getElementById("edgingLength").value);
var wastePercent = parseFloat(document.getElementById("wasteFactor").value);
var resultDiv = document.getElementById("borderResult");
var unitDisplay = document.getElementById("unitDisplay");
var summaryDisplay = document.getElementById("summaryDisplay");
if (isNaN(totalFeet) || isNaN(unitInches) || totalFeet <= 0 || unitInches <= 0) {
alert("Please enter valid positive numbers for length and unit size.");
return;
}
if (isNaN(wastePercent)) {
wastePercent = 0;
}
// Convert total feet to inches
var totalInches = totalFeet * 12;
// Calculate base units
var baseUnits = totalInches / unitInches;
// Add waste factor
var totalWithWaste = baseUnits * (1 + (wastePercent / 100));
// Round up since you can't buy half a brick/stone usually
var finalUnits = Math.ceil(totalWithWaste);
unitDisplay.innerHTML = finalUnits + " Units";
summaryDisplay.innerHTML = "Based on a " + totalFeet + " ft perimeter with " + unitInches + " inch edging pieces. " +
"Includes a " + wastePercent + "% allowance for cuts and breakage (" +
Math.ceil(baseUnits) + " base units + " + (finalUnits – Math.ceil(baseUnits)) + " extra).";
resultDiv.style.display = "block";
}
How to Use the Landscape Border Calculator
Planning a garden project requires precision, especially when purchasing materials like stone pavers, bricks, or plastic edging. Our Landscape Border Calculator is designed to help you determine exactly how many individual units you need to complete your garden perimeter without making multiple trips to the hardware store.
Understanding Border Measurements
To get an accurate result, you need three primary pieces of information:
Total Border Length: This is the entire perimeter of the area you wish to edge. Use a flexible measuring tape for curved garden beds.
Length of One Edging Unit: This is the length of a single brick, stone, or section of edging in inches. For example, a standard landscape brick is often 12 inches long.
Waste Allowance: It is standard practice to add 10% extra to account for cuts at corners, irregular shapes, or accidental breakage during installation.
The Math Behind the Border
The calculation follows a simple physics-based logic to ensure coverage. First, we convert the total linear footage into inches to match the unit size. Then, we divide that total length by the length of a single unit. Finally, we apply the waste percentage and round up to the nearest whole number.
Imagine you have a rectangular flower bed that measures 10 feet long and 5 feet wide. The total perimeter is 30 feet (10+10+5+5). You have chosen decorative stones that are 8 inches long each.
Convert 30 feet to inches: 30 × 12 = 360 inches.
Divide by unit length: 360 / 8 = 45 units.
Add 10% waste: 45 × 1.10 = 49.5 units.
Result: You should purchase 50 stones.
Tips for a Perfect Garden Edge
When installing your border, always start from the most visible corner or the center of a curve. If you are using interlocking plastic edging, remember to measure only the "exposed" length of the unit, as the overlap sections do not contribute to the total perimeter length. For stone borders, consider the "gap" or mortar joints if you are doing a professional masonry installation, as this might slightly reduce the number of physical bricks needed.