Screen Resolution & Size Checker
Detect your display resolution, viewport, DPR, and aspect ratio. Use test patterns to verify sharpness, scaling, and dead pixels.
Display information
Test patterns
Set OS scaling and browser zoom to 100% for the sharpest grid and ruler results. Physical pixel counts use CSS pixels × DPR.
How to read these numbers
Screen vs viewport
Screen resolution is what the OS reports for the display. Viewport is the browser content area and is usually smaller because of toolbars and window chrome.
Device pixel ratio
DPR above 1 means a HiDPI / Retina display: multiple physical pixels render each CSS pixel, which makes text and UI look sharper.
Test patterns
Use the 1px grid and checkerboard to spot blurry scaling. The ruler can be compared with a physical ruler after you enter the correct diagonal for PPI.
Frequently Asked Questions
Why do lines look blurry?
Non-native OS scaling or browser zoom often softens 1px lines. Try 100% scaling and zoom, then re-check the grid.
Is PPI exact?
PPI is calculated from reported screen pixels and the diagonal you enter. Measure the panel diagonal with a tape for best accuracy.
Does this upload anything?
No. Everything runs locally in your browser.