Why does this show a different number than my Windows display settings?

It should not. The headline figure multiplies the CSS size the browser reports by your pixel ratio, which undoes display scaling and lands back on the native panel size. Tools that print only the raw browser value show 1707x960 on a scaled 2560x1440 monitor, which is why their numbers look wrong.

What is the difference between CSS pixels and real pixels?

A CSS pixel is the unit web pages are laid out in. On a scaled or high density screen, one CSS pixel covers several hardware pixels, and the pixel ratio row tells you how many. A MacBook at 1512 CSS pixels wide with a ratio of 2 is really 3024 pixels across.

Why is my browser window smaller than my screen?

The browser window row measures the drawable area inside the tab, so it excludes the address bar, any open developer tools, and the window borders. The usable area row sits between the two: it is the full screen minus the taskbar or dock.

My resolution says non-standard. Is something wrong?

No. It just means the size does not match a named standard like 1080p or QHD. Ultrawide monitors, tablets in split view, and browser windows on scaled displays land on sizes that never got a marketing name. The pixel counts are still correct.

Does the aspect ratio explain the black bars in my games?

Often, yes. A 16:9 game rendered on a 21:9 ultrawide gets pillarboxed unless the game supports the wider ratio, and a 4:3 game on any modern panel does the same. Matching the game ratio to the row here tells you whether the bars come from the panel or from a game setting.

Why did the numbers change when I moved the window to another monitor?

Each display reports its own resolution and pixel ratio, and the browser reads whichever screen the window currently sits on. Moving between a laptop panel and an external monitor changes the reading, so check the tool on the display you actually care about.

Screen Resolution Checker

Check your screen resolution in real pixels, plus aspect ratio, pixel ratio, color depth and browser window size. Reads locally, nothing uploaded.

Vadim Cheban

The number below is your display in real hardware pixels, with display scaling already accounted for. The rows under it split the panel from the page, since the area a website can draw in is always smaller than the screen it sits on.

How to use

Open the page. The reading appears on its own. No permission prompt, no install, no button to press.
Read the headline number. That is your panel in real pixels, the same figure your display settings show. The label under it names the standard, like Full HD or QHD.
Check the smaller rows. Aspect ratio, pixel ratio and color depth describe the panel. The CSS pixels and browser window rows describe what a web page actually gets to draw on.

Why test this

Screen resolution is the first thing a support agent, a game forum, or a monitor return form asks for, and it is oddly hard to answer from memory. Digging through display settings takes longer than it should, and on a laptop plugged into a second monitor the answer depends on which screen the window is on. This page answers it the moment it loads. The reason to use it over the many one line resolution pages: those print the raw browser value, which display scaling has already changed. Set Windows to 150 percent on a 1440p monitor and they will confidently tell you your screen is 1707x960. Neither number is a monitor you can buy. This tool multiplies the browser value back out by the pixel ratio, so the headline matches your panel and your display settings agree with it. The rows underneath separate the panel from the page: your monitor is one size, the area a website gets to draw in is a smaller one, and knowing which is which explains most layout questions people bring to a forum.

What the results mean

The headline is your panel in hardware pixels, with the standard name under it. Full HD is 1920x1080, QHD is 2560x1440, and 4K UHD is 3840x2160. Aspect ratio is the shape of the panel: 16:9 for most monitors and laptops, 21:9 for ultrawides, 3:2 for many Surface and Framework laptops, 9:19.5 or thereabouts for phones held upright. Pixel ratio is how many hardware pixels sit under one CSS pixel. A ratio of 1 means no scaling, 2 is a typical Retina laptop, and values like 1.25 or 1.5 come from Windows display scaling. Color depth is bits per pixel across all channels, so 24-bit means 8 bits each for red, green and blue. CSS pixels is the size web pages are laid out against, usable area subtracts the taskbar or dock, and browser window is the drawable area inside the current tab. Drag the window edge and that last row updates live, which is a fast way to test how a site behaves at a given width.

FAQ

Why does this show a different number than my Windows display settings?: It should not. The headline figure multiplies the CSS size the browser reports by your pixel ratio, which undoes display scaling and lands back on the native panel size. Tools that print only the raw browser value show 1707x960 on a scaled 2560x1440 monitor, which is why their numbers look wrong.
What is the difference between CSS pixels and real pixels?: A CSS pixel is the unit web pages are laid out in. On a scaled or high density screen, one CSS pixel covers several hardware pixels, and the pixel ratio row tells you how many. A MacBook at 1512 CSS pixels wide with a ratio of 2 is really 3024 pixels across.
Why is my browser window smaller than my screen?: The browser window row measures the drawable area inside the tab, so it excludes the address bar, any open developer tools, and the window borders. The usable area row sits between the two: it is the full screen minus the taskbar or dock.
My resolution says non-standard. Is something wrong?: No. It just means the size does not match a named standard like 1080p or QHD. Ultrawide monitors, tablets in split view, and browser windows on scaled displays land on sizes that never got a marketing name. The pixel counts are still correct.
Does the aspect ratio explain the black bars in my games?: Often, yes. A 16:9 game rendered on a 21:9 ultrawide gets pillarboxed unless the game supports the wider ratio, and a 4:3 game on any modern panel does the same. Matching the game ratio to the row here tells you whether the bars come from the panel or from a game setting.
Why did the numbers change when I moved the window to another monitor?: Each display reports its own resolution and pixel ratio, and the browser reads whichever screen the window currently sits on. Moving between a laptop panel and an external monitor changes the reading, so check the tool on the display you actually care about.

Every measurement on this site comes from a documented browser API and a stated formula, and we are open about what a browser cannot see. Read how we test.

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