Developer tool
Screen Resolution Checker
See your screen resolution, browser viewport, pixel ratio, colour depth, touch support and user agent, with a reference of common device sizes.
Free, no sign-up. Runs in your browser; nothing is uploaded.
Reading your screen...
How to use the screen resolution checker
What your screen and browser look like to a website
Web designers and testers constantly ask "what size is this screen and what is the pixel ratio?" This page answers instantly using values your browser exposes, and it keeps updating when you resize the window or rotate the device.
What is shown
- Screen size in CSS pixels, and physical pixels calculated with the pixel ratio.
- Viewport width and height: the area your page actually has. This is what responsive breakpoints react to.
- Available area, which excludes taskbars and docks.
- Device pixel ratio (DPR), which tells you how dense the display is.
- Colour depth, orientation, touch points, platform, language, CPU thread count and memory when the browser reports them.
- Colour scheme and reduced motion preferences, which matter for dark mode and animation choices.
- The full user agent string.
Use the Copy report button to paste the details into a bug report or support ticket.
Why it matters for design
- Breakpoints: common widths are 375 to 430 for phones, 768 to 1024 for tablets and 1280 and above for desktops. Test each.
- Sharp images: a display with DPR 2 needs images twice the CSS size, or SVG, to look crisp.
- Touch targets: if touch is supported, use controls at least 44 by 44 pixels.
- Zoom: browser zoom changes the viewport and DPR values, so you can test zoom levels here.
Common resolutions
The table lists popular desktop, laptop, phone and tablet sizes in CSS pixels, so you can match a customer device to a layout width.
Privacy
These values are read in your browser and shown on the page. Nothing is sent to DEV3 or stored, though other websites can read the same information.
Frequently asked questions
Why is my screen size smaller than the monitor specification?
Browsers report CSS pixels, not physical ones. A 4K laptop at 200 percent scaling reports 1920 by 1080. The tool also shows the physical size by multiplying by the pixel ratio.
What is the device pixel ratio?
How many physical pixels make up one CSS pixel. Standard monitors are 1, many laptops 2 and many phones 3. It decides which image resolution looks sharp.
What is the difference between screen and viewport?
The screen is the whole display. The viewport is the visible area inside the browser window, which changes when you resize or zoom. Media queries use the viewport.
Why does the colour depth say 24?
It means 8 bits per channel of red, green and blue, around 16.7 million colours. Some displays report 30 or 32.
Can a website see this about me?
Yes, these values are available to any page you visit. This tool shows them only to you and does not store or send them.
Does the user agent show my real device?
It is a text the browser sends, which may be shortened or changed by privacy settings, so treat it as a hint.