Screen Size Checker
Check your screen's physical size and resolution. Run the browser-based check and follow its prompts to review the result.
Resolution and pixel ratio above are read from your browser. Browsers do not expose physical screen dimensions, so enter the diagonal from your device specifications to estimate pixel density.
Tool guide
About Screen Size Checker
Read browser-reported screen resolution, device pixel ratio, available screen area, orientation, and color depth. If you enter a physical diagonal from the device specifications, the tool estimates pixel density in PPI.
How to use this tool
- 1Review the browser's reported CSS-pixel screen size and device pixel ratio.
- 2Enter the display's physical diagonal in inches from a reliable device specification.
- 3Read the estimated PPI and compare it with the reported screen values; do not assume the browser knows the physical panel size.
How the tool works
The tool estimates physical pixel dimensions by multiplying browser screen CSS-pixel dimensions by device pixel ratio. It calculates pixel diagonal as √(pixel width² + pixel height²), then divides by the entered diagonal inches to estimate PPI. The browser does not expose actual physical dimensions directly, so the diagonal is user-supplied.
Worked real-world example
If estimated pixel dimensions are 3000 by 2000 and the screen diagonal is 15 inches, the diagonal pixel count divided by 15 gives an approximate pixel density.
Common scenarios and use cases
Inspect browser display metrics and make a rough pixel-density estimate from a known device diagonal.
Important details and limitations
Browser and operating system may round or scale reported metrics, and device pixel ratio can vary with zoom or display settings. The entered diagonal must describe the active display. PPI is an estimate, not a calibrated measurement.
Check the output unit as well as the number. If the result will be reused in another calculation, retain full precision where possible and round only at the end. For measurements governed by a technical specification, use the standard and tolerance required by that document.
Frequently asked questions
Can the browser read my screen's physical size?
No. You must supply the diagonal from the device specifications.
What is device pixel ratio?
It relates device pixels to CSS pixels used by web layout.
Is this the same as printer DPI?
No. PPI describes screen pixels per inch; DPI commonly describes physical printer dots.