What's My Browser Size?
See your browser viewport size in pixels, live as you resize the window.
Updates live as you resize the window — this is the browser's viewport size (the visible page area), not your monitor's full screen resolution. Nothing is sent to a server.
What is What's My Browser Size??
Shows the current width and height of your browser's visible page area, updating live as you resize the window — useful for checking a responsive breakpoint, reproducing a layout bug reported at a specific size, or confirming exactly how much space a page has to work with before you write a media query. The numbers shown are the viewport size (`window.innerWidth`/`window.innerHeight`), not your monitor's resolution — the viewport is what's left after the browser's tabs, address bar, bookmarks bar, and window chrome take their share. Everything is computed and displayed in your browser; nothing about your window size is sent to a server.
FAQ
No — this is the browser viewport (the visible page area inside the window), which is smaller than your full screen resolution once you account for the browser chrome, taskbar, and window borders.
Opening dev tools, a bookmarks sidebar, or split-screen view shrinks the space left for the page, so the viewport width/height updates live to reflect it.
Not exactly — device screen sizes are usually quoted in CSS pixels at a specific zoom/DPI, while this shows your current browser's actual viewport at whatever zoom level and window size you have right now. Resize the window or change zoom to approximate a target breakpoint.