How to use
- 1Open the page; your screen details appear automatically.
- 2Resize the browser window or rotate your device to watch the viewport update live.
- 3Copy the values for a bug report, design spec or support ticket.
Screen resolution vs viewport
Screen resolution is the size of your whole display in CSS pixels (e.g. 1920 × 1080). The viewport is the area inside the browser window where pages render — smaller because of the toolbars, tabs and scrollbars. Responsive CSS media queries are based on the viewport width, so that is the number designers and developers usually need.
Device pixel ratio (DPR) explained
High-density screens pack several physical pixels into each CSS pixel. An iPhone reporting 393 × 852 with a DPR of 3 actually has 1179 × 2556 physical pixels. To get the physical resolution, multiply the CSS size by the DPR. This is also why images look sharp only when served at 2× or 3× their display size on such screens — use srcset to deliver the right size.
Why your numbers may look “wrong”
Windows display scaling (125%, 150%) and browser zoom both change the reported values: a 2560 × 1440 monitor at 150% scaling reports 1707 × 960 in CSS pixels, with a DPR of 1.5. Reset browser zoom to 100% with Ctrl+0 (Cmd+0 on Mac) for comparable values. The page also shows color depth, orientation, touch support, OS, browser, time zone and language.
Frequently asked questions
How do I find my monitor’s native resolution?
Multiply the screen size shown here by the device pixel ratio. On Windows you can also check Settings → System → Display; on macOS, System Settings → Displays.
What are the most common screen resolutions?
On desktop, 1920 × 1080 remains the most common, followed by 1366 × 768, 1536 × 864 and 2560 × 1440. Phones typically report widths of 360–430 CSS pixels.
Why does the viewport change when I zoom?
Zooming changes the size of a CSS pixel, so fewer CSS pixels fit in the window and the reported viewport and DPR change.
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