What Is My Screen Resolution
A screen resolution tester that runs entirely in your browser. It reads your display size in pixels, reduces it to a display ratio, tells you whether you are in landscape or portrait, and separates the whole screen from the part your browser window actually occupies — useful for checking a monitor, picking a design breakpoint, or verifying what a website sees on your device.
Your own display and browser window size, measured in this browser tab with the standard browser APIs (screen.width / screen.height / window.innerWidth / window.innerHeight). Nothing is sent anywhere or stored.
Screen resolution in pixels
- Screen width (px)
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- Screen height (px)
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- Display ratio
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- Screen orientation
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- Browser screen width (px)
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- Browser screen height (px)
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Values update automatically when you resize the window or rotate your device.
Open the page
The six fields fill in automatically — screen width, screen height, display ratio, screen orientation, and the browser window width and height. No buttons to press first, no sign-in, no download.
Resize or rotate
Drag the browser window wider or narrower, or rotate your phone: the values update live. Hit "Check again" any time to force a fresh read. The screen size stays fixed while the browser size follows the window.
Read the ratio and orientation
The display ratio is the screen size reduced to its smallest whole-number pair — 1920×1080 becomes 16:9, 1280×1024 becomes 5:4. Orientation says whether the screen is wider than it is tall (landscape) or taller than wide (portrait).
How screen resolution is detected
- How does this page know my screen size?
- It reads your own browser's built-in screen.width and screen.height properties for the display, and window.innerWidth and window.innerHeight for the browser window. That is the same standard JavaScript every "check my resolution" page uses — the measurement happens on your device.
- What is the difference between screen size and browser size?
- Screen size is the whole display. Browser size is the part your page actually gets to use — smaller whenever browser toolbars, side panels, or another window take space. A 1920×1080 screen commonly shows a browser around 1920×950, and much less in a half-screen or split-view window.
- How is the display ratio calculated?
- By dividing both numbers by their greatest common divisor, so the ratio is exact: 2560×1440 reduces to 16:9, 800×600 to 4:3, 1080×1920 to 9:16. Odd sizes keep their exact ratio (1366×768 stays 683:384) instead of being rounded to a marketing label.
- Why is my phone showing smaller numbers than the box says?
- Browsers report sizes in CSS pixels, which modern high-density ("Retina") displays scale down from the native hardware pixel count, and the browser only ever sees its own window. The numbers here are the ones websites actually lay out against — which is usually what you want to know.
- Does it work on phones and tablets?
- Yes. Rotation is detected automatically: turn the device and the width and height swap, and the orientation line flips between landscape and portrait.
Privacy: your screen and window size are read locally by your browser and shown only to you — nothing is collected, stored, or transmitted. Common display sizes and their meanings are described above; exact values vary with your display, scaling setting, and window size.