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Screen Resolution Checker

Shows your device and CSS resolution, pixel ratio, aspect ratio, colour depth and pixel density in one place.

Screen Tests Nothing uploaded No sign-up Free, unlimited
Screen Tests tool
The test starts automatically — follow the prompts above.
In short This reports two resolutions and they are supposed to differ. CSS resolution is the coordinate space web pages lay out against; device resolution is the physical pixel grid. A phone reporting 390 × 844 at a pixel ratio of 3 really has 1170 × 2532 physical pixels, and both numbers are correct — the ratio is what maps one to the other and is why text on a modern phone looks sharp rather than tiny. On a desktop the same mechanism appears as display scaling. If the reported resolution does not match your monitor's specification, your system is scaling: set the display to its native resolution in the operating system, and set scaling separately if things are too small. Those are two different settings and running a panel below its native resolution to make text bigger is the wrong fix, because it makes everything soft. Native resolution plus scaling gives you large text and sharp edges; a lower resolution gives you large text and soft edges.

How to use the Screen Resolution Checker

  1. The test starts on its own — no button to press and nothing to install.
  2. Follow the prompt in the test panel and watch the readings update live.
  3. Press Reset to start over with a clean slate.

About the Screen Resolution Checker

The Screen Resolution Checker shows your device and CSS resolution, pixel ratio, aspect ratio, colour depth and pixel density in one place. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Finding your exact resolution for a support ticket or bug report.
  • Working out a display's pixel density before buying.
  • Checking whether a monitor is running below its native resolution.

Explained in our guides

All guides

Frequently asked questions

Why are there two different resolutions?
CSS resolution is what web pages lay out against; device resolution is the physical pixel grid. A phone reporting 390 × 844 at a 3× pixel ratio really has 1170 × 2532 pixels. Both matter, for different reasons.
The resolution does not match my monitor's specification.
Your system is scaling. Set the display to its native resolution in the operating system, and set scaling separately if things are too small — those are two different settings and people often confuse them.
Is there a limit on how often I can use the Screen Resolution Checker?
Free, unlimited, and no email address required. You can use it a hundred times a day and nothing changes.
Is my data uploaded anywhere?
No. The Screen Resolution Checker runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
Who is the Screen Resolution Checker for?
The jobs it is built for: finding your exact resolution for a support ticket or bug report. Working out a display's pixel density before buying. Checking whether a monitor is running below its native resolution. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Do I need to install anything to run this test?
No installation, no extension and no driver. The Screen Resolution Checker uses the browser's own device APIs and begins as soon as the page loads, so there is nothing to press first. Press Reset at any point to start over with a clean slate.

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