What Is My Browser Window Size
A live window size meter that runs entirely in your browser. It shows the outer size of your browser window, the inner size of the page viewport inside it, and the window's left and top coordinates on your screen — the exact numbers a web page sees, updating as you drag the window. Useful for checking a layout breakpoint, sizing a screenshot, or comparing window size against screen size on any device.
Your current browser window size, measured live in this tab with the standard browser properties (window.outerWidth/outerHeight, window.innerWidth/innerHeight, screenX/screenY). Everything is computed on your device; nothing is sent anywhere or stored.
Your window size is
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Resizing the window updates the values automatically. If you only moved the window, press Re-measure to pick up the new coordinates. Outer size includes the window frame and browser chrome; inner size is the page viewport; coordinates can be negative on multi-monitor setups.
Open the page
The three fields fill in immediately — outer window size, inner window size, and the left, top screen coordinates of the window. No buttons to press first, no sign-in, nothing to upload.
Resize the window
Drag an edge of your browser and watch the values follow. The inner size is the viewport your web content gets; the outer size adds the window frame, tabs, and toolbars. If you only move the window, press Re-measure to refresh its coordinates.
Copy the numbers
Press Copy sizes to put all three measurements on your clipboard as clean text — width x height in pixels for outer and inner, plus the left, top pair — ready to paste into a design doc, bug report, or stylesheet.
How window size is detected
- How does this page know my window size?
- It reads your browser's own standard properties: window.outerWidth and window.outerHeight for the whole window, window.innerWidth and window.innerHeight for the page viewport inside it, and window.screenX and window.screenY (window.screenLeft and window.screenTop on older browsers) for where the window sits on screen. The measurement happens on your device — the same JavaScript every window-size checker uses.
- What is the difference between outer and inner size?
- Outer size is the entire browser window including its frame, tab strip, and toolbars. Inner size is only the area your web page is laid out in — always smaller by roughly the height of the browser chrome. When developers talk about a viewport for responsive design, they mean the inner size.
- Why are my screen coordinates negative?
- That is normal on multi-monitor setups. Coordinates count pixels from the top-left corner of your main screen, so a window placed on a monitor above or to the left of it reports a negative top or left value.
- Why are the numbers smaller than my monitor's native resolution?
- Browsers report sizes in CSS pixels, which high-density displays scale down from hardware pixels, and a window never covers the whole screen anyway. The inner size here is exactly what websites lay out against, which is usually the number you actually want.
- Does it work on phones and tablets?
- Yes. Rotate the device or enter split-view and the values update live. On mobile the outer and inner sizes are often identical because there is no separate window frame.
Privacy: your window size and position are read locally by your browser and shown only to you — nothing is collected, stored, or transmitted. Exact values depend on your display, OS, browser, zoom level, and window size.