What it does
WhatIsMyScreenSize.com is a browser-based tool that detects and displays a device's screen dimensions, resolution, pixel density, aspect ratio, and viewport size without collecting or storing any user data. It also includes a reference database of device specs and a set of related calculators for tasks such as PPI calculation, monitor scaling, and aspect ratio conversion.
Use cases
- Checking your current screen's resolution, DPI, and aspect ratio instantly in the browser without installing software.
- Finding the physical size of a monitor in diagonal inches when no tape measure is available.
- Looking up display specifications for specific phone models such as the iPhone 18 Pro or Galaxy S25 before buying or developing for them.
- Testing viewport breakpoints and CSS viewport units when building or debugging responsive web layouts.
- Comparing foldable device inner and outer screen sizes to plan responsive designs for cover and inner panels.
Who it is for
- Web developers and designers who need accurate viewport and resolution data for responsive layout work.
- Consumers researching device screen specs before purchasing a phone, tablet, or monitor.
- General users who simply want to know the size or resolution of the screen they are currently using.
Alternatives and comparison
No named competitors are identified on the page. General alternatives include browser developer tools built into Chrome, Firefox, and Edge, which can surface viewport and pixel ratio figures but require opening a dedicated panel. Other what-is-my-screen sites exist in this category; comparisons between them cannot be made from the available page content alone.
- What Is My Browser
- A general browser information tool that includes screen and viewport data among many other browser properties; less focused on display specifications than this site.
