Calculate Display Size

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Screen Size & Display Dimensions Calculator

Calculated Dimensions

Display Width –
Display Height –
Total Screen Area –
function calculateDisplaySize() { var diag = parseFloat(document.getElementById('diagInput').value); var wRatio = parseFloat(document.getElementById('ratioW').value); var hRatio = parseFloat(document.getElementById('ratioH').value); if (isNaN(diag) || isNaN(wRatio) || isNaN(hRatio) || diag <= 0 || wRatio <= 0 || hRatio <= 0) { alert("Please enter valid positive numbers for all fields."); return; } // Calculation using Pythagorean theorem // diag^2 = (wRatio * x)^2 + (hRatio * x)^2 // diag^2 = x^2 * (wRatio^2 + hRatio^2) var x = Math.sqrt(Math.pow(diag, 2) / (Math.pow(wRatio, 2) + Math.pow(hRatio, 2))); var width = x * wRatio; var height = x * hRatio; var area = width * height; document.getElementById('resWidth').innerHTML = width.toFixed(2) + ' inches (' + (width * 2.54).toFixed(2) + ' cm)'; document.getElementById('resHeight').innerHTML = height.toFixed(2) + ' inches (' + (height * 2.54).toFixed(2) + ' cm)'; document.getElementById('resArea').innerHTML = area.toFixed(2) + ' sq. inches (' + (area * 6.4516).toFixed(2) + ' sq. cm)'; document.getElementById('displayResults').style.display = 'block'; }

Understanding Display Size and Dimensions

When shopping for a TV, monitor, or smartphone, the "size" advertised is almost always the diagonal measurement from one corner to the opposite corner. However, this number doesn't tell you the actual width and height of the screen. Two screens with the same diagonal measurement can have vastly different viewing areas depending on their aspect ratio.

Common Aspect Ratios

  • 16:9 (Widescreen): The standard for modern TVs, computer monitors, and high-definition video content.
  • 21:9 (Ultrawide): Popular for cinematic experiences and productivity monitors, offering more horizontal space.
  • 4:3 (Standard): The ratio of older "square" TVs and early computer monitors.
  • 16:10: Often found in professional laptops and tablets, providing a bit more vertical space than standard 16:9.

How the Calculation Works

Calculating the exact width and height of a screen requires the Pythagorean theorem (a² + b² = c²). Since we know the ratio between the width (a) and height (b), and the diagonal (c), we can solve for the specific dimensions:

  1. Square the diagonal measurement.
  2. Square both parts of the aspect ratio and add them together.
  3. Divide the squared diagonal by that sum.
  4. Take the square root of the result to find the multiplier.
  5. Multiply the width ratio and height ratio by that multiplier.

Example Calculation

Suppose you have a 32-inch monitor with a 16:9 aspect ratio:

Using the formula, the width would be approximately 27.89 inches and the height would be 15.69 inches. The total surface area is roughly 437.5 square inches. Knowing these measurements is crucial for determining if a screen will fit on your desk or wall mount.

Why Surface Area Matters

Surface area is the best metric for comparing "how much screen" you actually get. For instance, a 50-inch 16:9 TV has significantly more viewing area than a 50-inch 21:9 ultrawide monitor. This is because a square-like shape maximizes area for a given diagonal measurement compared to a long, thin rectangle.

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