Perimeter Calculator

.perimeter-calc-container { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; max-width: 800px; margin: 20px auto; padding: 25px; border: 1px solid #e1e1e1; border-radius: 12px; background-color: #ffffff; box-shadow: 0 4px 6px rgba(0,0,0,0.05); } .perimeter-calc-container h2 { color: #2c3e50; text-align: center; margin-bottom: 25px; font-size: 28px; } .calc-row { margin-bottom: 20px; } .calc-row label { display: block; font-weight: 600; margin-bottom: 8px; color: #34495e; } .calc-row select, .calc-row input { width: 100%; padding: 12px; border: 2px solid #ddd; border-radius: 6px; font-size: 16px; box-sizing: border-box; transition: border-color 0.3s; } .calc-row input:focus { border-color: #3498db; outline: none; } .calc-btn { width: 100%; background-color: #3498db; color: white; padding: 15px; border: none; border-radius: 6px; font-size: 18px; font-weight: bold; cursor: pointer; transition: background-color 0.3s; } .calc-btn:hover { background-color: #2980b9; } .calc-result { margin-top: 25px; padding: 20px; background-color: #f8f9fa; border-left: 5px solid #3498db; border-radius: 4px; display: none; } .calc-result h3 { margin: 0 0 10px 0; color: #2c3e50; } .result-val { font-size: 24px; font-weight: bold; color: #27ae60; } .shape-inputs { display: none; } .active-shape { display: block; } .geo-article { margin-top: 40px; line-height: 1.6; color: #444; } .geo-article h2 { color: #2c3e50; border-bottom: 2px solid #eee; padding-bottom: 10px; } .geo-article h3 { color: #2980b9; margin-top: 25px; } .formula-box { background: #f1f1f1; padding: 15px; border-radius: 8px; font-family: "Courier New", Courier, monospace; margin: 15px 0; }

Advanced Perimeter Calculator

Rectangle Square Circle (Circumference) Triangle (Scalene/General) Regular Polygon

Total Perimeter:

0

Understanding Perimeter Calculation

Perimeter is the total distance around the outside of a two-dimensional shape. Whether you are calculating the amount of fencing needed for a backyard, the trim required for a window, or the distance around a running track, understanding perimeter is a fundamental skill in geometry and real-world construction.

Common Perimeter Formulas

Depending on the geometry of the object, different mathematical formulas are applied:

Rectangle: P = 2 × (Length + Width)
Square: P = 4 × Side
Circle: C = 2 × π × Radius
Triangle: P = a + b + c
Regular Polygon: P = n × Side Length

Practical Examples

Example 1: The Backyard Fence
Suppose you have a rectangular garden that is 20 meters long and 15 meters wide. To find the amount of fencing required:
Calculation: 2 × (20 + 15) = 2 × 35 = 70 meters.

Example 2: The Circular Table
If you need to put decorative tape around the edge of a circular table with a radius of 3 feet:
Calculation: 2 × 3.14159 × 3 ≈ 18.85 feet.

Why Precision Matters

In construction and manufacturing, perimeter calculations must be precise to avoid material waste. Our calculator provides high-precision results for irregular triangles and regular polygons alike, ensuring your projects are measured accurately every time.

function switchShape() { var selector = document.getElementById('shapeSelector'); var selectedValue = selector.value; var allInputs = document.getElementsByClassName('shape-inputs'); for (var i = 0; i < allInputs.length; i++) { allInputs[i].classList.remove('active-shape'); } document.getElementById('inputs-' + selectedValue).classList.add('active-shape'); document.getElementById('perimeterResult').style.display = 'none'; } function performCalculation() { var shape = document.getElementById('shapeSelector').value; var result = 0; var formula = ""; var isValid = true; if (shape === 'rectangle') { var l = parseFloat(document.getElementById('rectLength').value); var w = parseFloat(document.getElementById('rectWidth').value); if (!isNaN(l) && !isNaN(w)) { result = 2 * (l + w); formula = "Formula: 2 × (" + l + " + " + w + ")"; } else { isValid = false; } } else if (shape === 'square') { var s = parseFloat(document.getElementById('sqSide').value); if (!isNaN(s)) { result = 4 * s; formula = "Formula: 4 × " + s; } else { isValid = false; } } else if (shape === 'circle') { var r = parseFloat(document.getElementById('circRadius').value); if (!isNaN(r)) { result = 2 * Math.PI * r; formula = "Formula: 2 × π × " + r; } else { isValid = false; } } else if (shape === 'triangle') { var a = parseFloat(document.getElementById('triA').value); var b = parseFloat(document.getElementById('triB').value); var c = parseFloat(document.getElementById('triC').value); if (!isNaN(a) && !isNaN(b) && !isNaN(c)) { result = a + b + c; formula = "Formula: " + a + " + " + b + " + " + c; } else { isValid = false; } } else if (shape === 'polygon') { var n = parseFloat(document.getElementById('polySides').value); var sl = parseFloat(document.getElementById('polyLength').value); if (!isNaN(n) && !isNaN(sl)) { result = n * sl; formula = "Formula: " + n + " sides × " + sl; } else { isValid = false; } } if (isValid) { document.getElementById('resultValue').innerHTML = result.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 4}); document.getElementById('formulaUsed').innerHTML = formula; document.getElementById('perimeterResult').style.display = 'block'; } else { alert("Please enter valid numeric values for all fields."); } }

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