Display Size Calculator
Calculate width and height from screen diagonal in inches and centimeters, to find the right monitor size for your desk setup. GDPR-compliant.
Your inputs are processed in your browser and are not transmitted to our servers. Note: third-party resources (e.g. advertising and analytics from Google/Cloudflare) and an optional PayPal donation link may transfer data when loading or when clicked. Browser extensions or plugins may be able to read content that is visible in the input fields.
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How to use this tool (video)
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Display size calculator
The display size calculator derives width and height from the screen diagonal, in inches and centimeters. It also computes the aspect ratio and, on request, the pixel density (PPI) and dot pitch.
Convert diagonal to width and height
Enter the diagonal of your monitor, laptop or TV and choose the aspect ratio. The tool immediately returns the physical width and height, so you can see whether a 27 inch 16:9 display really fits on your desk.
Calculate PPI and dot pitch
Add the resolution in pixels and the calculator computes the pixel density (PPI). Higher PPI means a sharper image. The dot pitch shows the distance between two pixels in millimeters.
Analyze my device
The "my device" mode reads the current device values automatically and separates them into three clean groups: the native screen resolution, the browser CSS viewport and the physical size. The tool detects the first two on its own. The browser cannot measure physical size automatically: measure the visible display area with a ruler (corner to corner) and enter the value in centimeters. From that the tool computes PPI, dot pitch and the physical width and height.
Frequently asked questions
How does the tool derive width and height from the diagonal?
From the diagonal and the aspect ratio, the physical width and height can be derived using the Pythagorean theorem. The tool performs this calculation immediately, in inches and centimeters.
What does PPI mean?
PPI stands for pixels per inch and describes the pixel density of a screen. The higher the value, the sharper the image appears. The tool computes the PPI from the resolution and the physical size.
What is dot pitch?
Dot pitch is the distance between two pixels, given in millimeters. It is the counterpart to pixel density and is also calculated from the resolution and size.
How does the My device mode work?
The mode reads the native resolution and the CSS viewport of your device automatically. The browser cannot measure the physical screen size, so you enter it once in centimeters.
Do I have to measure values by hand?
Only the physical size of your screen has to be measured once with a ruler and entered in centimeters. All other values are detected automatically by the tool.
Are my device data transferred anywhere?
No. All calculations run entirely in your browser. Your device data are not transmitted to our server or stored.