What is my screen resolution?
This is your whole screen measured in CSS pixels, which is not the same as the resolution your monitor advertises. Display scaling sits in between: at 150 per cent scaling a 3840 pixel wide panel reports 2560. If you want the number your browser is actually painting into, that is the viewport, on its own page.
What this number actually means
The figure above comes from screen.width and screen.height, and it is measured in CSS pixels, not necessarily in the physical pixels on the panel. Multiply it by your device pixel ratio to get the physical count: a MacBook reporting 1512 by 982 at a ratio of 2 is driving 3024 by 1964 real pixels. The Available line beneath it subtracts space permanently claimed by the operating system, such as the Windows taskbar or the macOS menu bar.
Your screen resolution is shown above in pixels, width by height. This is the full size of your display as your browser sees it, for example 1920 by 1080 or 2560 by 1440. It is the total canvas of your monitor or device screen, not the size of the browser window.
There is a subtlety worth knowing: on high-density (Retina) displays, the resolution your browser reports is often the logical resolution, not the raw physical pixel count. A screen with twice the physical pixels reports the same logical size but at a device pixel ratio of 2, so the extra pixels sharpen the image rather than fitting more content.
This differs from your viewport size, which is only the visible area inside the browser window after toolbars and, on desktop, any space you have not maximised. If you are sizing a layout, the viewport is usually what matters; the screen resolution tells you the hardware you are working with.
How a website reads this
This is the exact call a page makes. Nothing else is involved, and nothing is sent anywhere: the value is read in your browser and displayed to you.
screen.width and screen.heightThe full screen in CSS pixels, not the browser window and not the panel's physical pixels. On a scaled display these numbers are smaller than the hardware resolution printed on the box, which is why a 4K monitor commonly reports 2560 by 1440 or even 1920 by 1080.
- Needs your permission
- No, it is read silently
- Can it be faked
- Partly. Not settable from a page, but Firefox's resistFingerprinting and Tor Browser report rounded or fixed values, and some extensions overwrite the properties.
- Contribution to a fingerprint
- About 4.5 bits, our own estimate. Our estimate. A handful of sizes cover most visitors, but the long tail of unusual resolutions is genuinely distinctive, and combining width, height and colour depth compounds it. How we estimate this.
What each browser does with it
The same call does not give the same answer everywhere. Several browsers withhold, round or cap this value on purpose, so a blank or suspiciously round result is usually a privacy decision rather than a fault.
| Browser | What it reports |
|---|---|
| Chrome, Edge, Safari | Report the real scaled screen size. |
| Firefox with resistFingerprinting | Reports the window size rounded to a coarse grid instead of the screen, so many users report the same value. |
| Tor Browser | Letterboxes the content area to fixed step sizes, so the reported dimensions are shared by many users on purpose. |
How does my screen resolution compare?
These are the reported figures for the most common classes of display, and the physical pixels behind them once the device pixel ratio is applied.
| Display | Usually reports | Physical pixels |
|---|---|---|
| Full HD monitor at 100 percent scaling | 1920 x 1080 (ratio 1) | 1920 x 1080 |
| Full HD monitor at 125 percent scaling | 1536 x 864 (ratio 1.25) | 1920 x 1080 |
| 1440p monitor at 100 percent scaling | 2560 x 1440 (ratio 1) | 2560 x 1440 |
| 4K monitor at 150 percent scaling | 2560 x 1440 (ratio 1.5) | 3840 x 2160 |
| 13 inch MacBook style Retina laptop | About 1470 to 1710 wide (ratio 2) | Double the reported figure in each direction |
| Modern phone in portrait | About 390 to 430 wide (ratio 2 to 3) | Roughly 1080 to 1290 wide |
Two very different monitors can therefore report the same numbers. Resolution on its own does not identify the panel, only the CSS canvas your operating system decided to present.
How do I check my monitor resolution outside the browser?
On Windows, right click the desktop and choose Display settings. The Display resolution dropdown shows the native panel resolution, and the Scale setting above it explains any gap between that figure and what your browser reports.
On macOS, open System Settings then Displays. Hold Option and click Scaled to reveal the full list including the true native resolution, which is otherwise hidden behind Apple's More Space and Larger Text presets.
On Linux, xrandr in a terminal lists every connected output with its current and available modes.
If the operating system number is larger than the one on this page, the difference is display scaling, and the ratio between the two is exactly your device pixel ratio.
Why does my browser report the wrong screen resolution?
Usually it is not wrong, it is measuring something else. The browser reports CSS pixels, a layout unit, while your monitor specification quotes physical pixels. Display scaling sits between them, which is why a 4K panel at 150 percent scaling reports 2560 by 1440.
A second cause is a multi monitor setup. screen.width describes the display the browser window currently sits on, so dragging the window to your second monitor changes the reading.
A third is deliberate. Tor Browser and Firefox with resistFingerprinting round or letterbox the reported size so it falls into one of a handful of common buckets, which means the value is intentionally not yours.
What can a website learn about me from my screen resolution?
More than you might expect, because unlike a window size it stays constant across visits. A site sees a fixed number every time you return, which makes it a durable component of a device fingerprint.
Its strength depends on how ordinary the value is. 1920 by 1080 is shared by an enormous number of people and gives away almost nothing. A resolution produced by an unusual scaling setting, an ultrawide panel or a rotated display is far rarer and narrows the crowd substantially.
Combined with the device pixel ratio, colour depth and the available area (which reveals your taskbar position and size), the display group as a whole is one of the more informative fingerprinting clusters that requires no permission at all. That is why the anti fingerprinting mode in privacy browsers targets it directly.
What you should know
Why sites collect it
Sites read your screen resolution to serve appropriately sized images, choose responsive layouts, decide whether a design fits, and gather analytics on the displays their audience uses so they can design for the common cases.
Privacy implications
Screen resolution is a meaningful fingerprinting signal because there are many possible values and yours tends to stay constant. Combined with your device pixel ratio, colour depth and browser it materially narrows down your device. Unusual resolutions stand out more than common ones.
How to change or hide it
You can change your resolution in your operating system display settings, though that affects everything you see, not just what sites read. Privacy browsers may report a rounded or common resolution to reduce distinctiveness. There is no per-site control.
Frequently asked questions
Why does my resolution look smaller than my monitor's specs?
On high-density displays the browser reports a logical resolution and applies a device pixel ratio, so a sharp 4K panel may report a smaller number with a ratio of 2.
How many pixels is my screen?
In CSS pixels, the figure at the top of this page. In physical pixels, multiply both numbers by your device pixel ratio: 1512 by 982 at a ratio of 2 is 3024 by 1964 real pixels.
What is the difference between screen resolution and viewport?
Screen resolution is your whole display; the viewport is only the visible content area inside the browser window. Layouts usually respond to the viewport.
Why did my resolution change when I moved the window?
screen.width describes the display the window is currently on, so a multi monitor setup reports different values depending on which screen holds the browser.
Sources
Browser behaviour changes and vendors cap these values differently, so the claims above that are not self-evident are checked against the specifications and vendor documentation below.
Last checked on . How these values are measured and estimated is set out on the methodology page.
Something wrong here? Tell us what your browser reports and it gets corrected.