What is my screen resolution?
// My System Information on the Internet
The number of pixels wide and tall that make up your screen (e.g. 1920×1080).
The size of your actual visible browser window — different from your full screen resolution if your browser isn't maximized.
What is screen resolution?
Screen resolution describes the total number of pixels your display is made up of, expressed as width × height. A resolution of 1920×1080 — often called Full HD or 1080p — means the screen has 1,920 columns of pixels and 1,080 rows, for a total of just over two million individual pixels.
Higher resolutions pack more pixels into the same physical space, which generally means sharper text and images. A 2560×1440 display (QHD) has more than twice as many pixels as 1280×720 (HD), even if both monitors are the same physical size.
Browsers can read your screen resolution directly from the operating system at any time using window.screen.width and window.screen.height. No permission dialog appears and no user action is needed — it is available to every website you visit, the moment the page loads.
Screen resolution vs viewport size — what is the difference?
Screen resolution is your monitor's total pixel count — a fixed property of the hardware. Viewport size is the usable area inside your browser window at this moment, and it changes constantly as you resize the window, open or close browser toolbars, or switch between apps.
A concrete example: on a 1920×1080 laptop, if your browser window is not maximized — say it only takes up three quarters of the screen — your viewport might be 1440×900. Open the browser's developer tools panel and it shrinks further. These two numbers can differ significantly from your screen resolution.
On a phone in portrait orientation, the viewport is narrow and tall. Rotate to landscape and the viewport becomes wide and short — even though the screen resolution itself has not changed, just which axis is which.
Why do websites care about your screen size?
The primary use is responsive design. A layout that works well at 1440 pixels wide will not work on a 390-pixel phone screen without adjustment. Websites use CSS breakpoints triggered by viewport dimensions to rearrange content — collapsing navigation menus, stacking columns, enlarging tap targets — so the page is usable on any device.
Image sizing is another significant use. Serving a 2400-pixel-wide hero image to a phone wastes bandwidth and slows the page. The srcset attribute lets websites serve different image sizes based on the viewport — a small version to phones, a full-size version to large desktop screens.
Analytics teams also track screen and viewport distributions to understand what sizes their audience uses — which directly informs design decisions, minimum supported screen widths, and where to focus testing effort.
Screen size and device fingerprinting
Your screen resolution and viewport size are two more data points that contribute to the broader picture a website can build about your device. Combined with your browser, OS, language, timezone, and other signals, a specific combination of values — including screen dimensions — can make your device statistically uncommon enough to identify across visits without a cookie.
This is the same fingerprinting concept discussed in more depth on our browser page and OS page.
Frequently asked questions
Common questions about screen resolution, viewport size, and what websites can see.
What is my screen resolution?
Your screen resolution is the total number of pixels your display is made up of, expressed as width × height. A resolution of 1920×1080 means the screen is 1,920 pixels wide and 1,080 pixels tall. Browsers can read this directly from the device without any permission, and it is available to any website you visit.
What's the difference between screen resolution and viewport size?
Screen resolution is your monitor's full pixel count. Viewport size is the usable area inside your browser window — smaller when the browser is not maximized, or when toolbars and sidebars take up space. Websites use viewport size to lay out content, not screen resolution, since that's the actual space they have to work with.
Why does a website need to know my screen size?
Websites use screen and viewport dimensions for responsive design — adjusting layouts, font sizes, and image sizes to fit the space available. A site serving a 1920-pixel-wide image to a 360-pixel-wide phone wastes bandwidth and looks wrong; knowing the dimensions lets it serve the right asset for the context.
What is a 'common' screen resolution today?
1920×1080 (Full HD) remains the most common desktop resolution. Laptops vary widely — 1366×768, 1536×864, and 2560×1600 are all common depending on age and tier. Mobile screen dimensions vary even more, from small phones around 360×800 to large phones at 430×932 or more. There is no single dominant resolution on mobile.
Does my screen resolution change when I rotate my phone?
The underlying screen resolution stays the same — the physical pixels do not change. What changes is which dimension is reported as width and which is height, since the browser rotates its coordinate system. The viewport size also changes, since a landscape orientation gives more horizontal space and less vertical space.
Your screen size is just one of many signals shared automatically with every site you visit. See everything else this connection reveals →