Utilore

Screen Resolution

Your screen resolution is shown at the top, exactly as the browser reports it. Below it are the real pixel count, the pixel density that explains the difference, the aspect ratio, the refresh rate and the size of the browser window. Resize the window and the numbers follow.

Everything below is read from your own browser. Resize the window and the numbers change with it.

— Screen, CSS pixels

Screen, real pixels
—
Pixel density
—
Aspect ratio
—
Megapixels
—
Page area
—
Browser window
—
Colour depth
—
Refresh rate
—
Orientation
—

Nothing here is sent anywhere: the page reads your own browser and shows you what it read. That is also why the refresh rate is measured by counting frames for half a second rather than asked for — browsers do not report it.

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How to use

  1. The big number is your screen in CSS pixels — the size the browser works in.
  2. «Screen, real pixels» is that number multiplied by the pixel density. This is the figure printed on a monitor's box.
  3. «Page area» is what a web page actually gets: the window minus toolbars and scrollbars. This is the number to use when a site asks what resolution you are viewing at.
  4. Resize the browser window or turn a phone sideways and watch which numbers change and which do not.

Good to know

Why the browser says 390×844 and the box says 1170×2532

Because they are counting different things. The browser reports CSS pixels, a unit of apparent size, so that text stays readable across screens; the box counts the physical dots in the panel. Modern phone screens pack three physical dots into one CSS pixel, which is what the pixel density line means — at a density of 3, a 390-wide screen really has 1170 dots across. On a desktop the same effect comes from display scaling: set Windows to 125 % and a 1920-pixel monitor reports 1536 to the browser. Both numbers are true; they just answer different questions.

Three sizes, and which one you want

The screen is the whole display. The browser window is smaller — it excludes whatever the operating system keeps, and on a maximised window on Windows it is a few pixels bigger than the screen because the frame hangs off the edges. The page area is smaller still, because toolbars, tab strips and scrollbars eat into it. When a site or a designer asks for «your resolution» they usually mean the screen; when something looks broken and you are asked what width you are viewing at, they mean the page area.

The refresh rate is measured, not asked for

Browsers do not expose the refresh rate, so this page counts how many frames it can draw in half a second. The result is rounded to the nearest common rate: a raw measurement of 59.7 is a 60 Hz screen with measurement noise, and showing 59.7 would be presenting the noise as a fact. The measurement can read low if the tab is in the background or the machine is busy, and on some laptops the rate itself changes to save battery — refresh the page if the number looks wrong.

Frequently asked questions

What is my screen resolution?

The number at the top of this page, in CSS pixels — that is what your browser sees. The real, physical resolution is the line below it, and if the two differ, the pixel density line says by how much.

Why is my 4K monitor showing 2560×1440?

Display scaling. At 150 % scaling a 3840-pixel monitor reports 2560 to applications, so that text and buttons are not a third of their intended size. The panel still has 3840 dots; the «real pixels» line shows them.

Does the page area change if I zoom?

Yes, and that is expected: zooming changes how many CSS pixels fit on the screen. Zoom in and the page area gets smaller in CSS pixels even though the window has not moved. The screen line does not change.

The refresh rate looks wrong.

Reload the page and keep this tab in the foreground. Browsers throttle animation in background tabs, so a measurement taken while you were elsewhere reads low. Some laptops also lower the refresh rate on battery, in which case the number is right and the screen really has slowed down.

Is any of this sent anywhere?

No. Everything on this page is read from your own browser and displayed back to you. Nothing is sent to a server, stored or logged, and the page works with the network switched off.

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