Monitor Dimension Calculator

Calculate the precise width, height, and total screen area of any display based on diagonal size and aspect ratio.

Diagonal Size (inches)

Aspect Ratio (Width)

Aspect Ratio (Height)

Screen Specifications:

Width:

in ( cm)

Height:

in ( cm)

Total Screen Area:

sq. in ( sq. cm)

function calculateMonitorDimensions() { var diag = parseFloat(document.getElementById('diagonalSize').value); var rW = parseFloat(document.getElementById('ratioWidth').value); var rH = parseFloat(document.getElementById('ratioHeight').value); if (isNaN(diag) || isNaN(rW) || isNaN(rH) || diag <= 0 || rW <= 0 || rH <= 0) { alert("Please enter valid positive numbers for all fields."); return; } // Using Pythagorean theorem: w^2 + h^2 = d^2 // Since ratio is rW:rH, then w = (rW/rH) * h // ((rW/rH) * h)^2 + h^2 = d^2 // h^2 * ((rW/rH)^2 + 1) = d^2 // h = sqrt( d^2 / ((rW/rH)^2 + 1) ) var angle = Math.atan(rH / rW); var heightIn = diag * Math.sin(angle); var widthIn = diag * Math.cos(angle); var areaIn = widthIn * heightIn; var heightCm = heightIn * 2.54; var widthCm = widthIn * 2.54; var areaCm = areaIn * 6.4516; document.getElementById('outWidthIn').innerText = widthIn.toFixed(2); document.getElementById('outWidthCm').innerText = widthCm.toFixed(2); document.getElementById('outHeightIn').innerText = heightIn.toFixed(2); document.getElementById('outHeightCm').innerText = heightCm.toFixed(2); document.getElementById('outAreaIn').innerText = areaIn.toFixed(2); document.getElementById('outAreaCm').innerText = areaCm.toFixed(2); document.getElementById('resultsArea').style.display = 'block'; }

Understanding Monitor Dimensions

When shopping for a new display, the "diagonal size" often hides the true physical presence of the screen. A 27-inch monitor with an ultra-wide aspect ratio will have a significantly different height and total surface area than a 27-inch monitor with a standard 16:9 aspect ratio. This calculator helps you determine the physical footprint of a screen before you buy.

How the Calculation Works

The math behind monitor dimensions relies on the Pythagorean theorem ($a^2 + b^2 = c^2$). Since the diagonal is the hypotenuse ($c$), and the aspect ratio provides the relationship between the width ($a$) and height ($b$), we can solve for the exact measurements in inches or centimeters.

Common Aspect Ratios

16:9 (Widescreen): The standard for most modern monitors and TVs. Ideal for movies and gaming.
21:9 (Ultrawide): Provides a cinematic field of view and extra horizontal workspace for productivity.
16:10: Popular in professional and business laptops, offering more vertical space for reading documents.
4:3: The "classic" square-like ratio used in older CRT monitors and some modern tablets.

Example: 24-inch Monitor (16:9)

If you have a standard 24-inch 16:9 monitor, the math reveals:

Width: ~20.92 inches (53.13 cm)
Height: ~11.77 inches (29.89 cm)
Total Area: ~246.13 square inches

Why Screen Area Matters

Screen area is a better metric for "usable space" than the diagonal alone. For instance, a 32-inch monitor with a 16:9 ratio has about 437 square inches of space, while a 34-inch ultrawide (21:9) actually has roughly 415 square inches. Despite having a larger diagonal number, the ultrawide has less total surface area because it is shorter vertically.

Practical Tips for Choosing a Size

When selecting a monitor, consider your desk depth. For a 27-inch monitor, a desk depth of at least 24 inches is recommended. If you are moving to a 32-inch or 43-inch screen, you may need 30 inches or more of depth to maintain a comfortable viewing distance and avoid eye strain.