What Is My Screen Size?
Your screen resolution, browser viewport, device pixel ratio, aspect ratio, and color depth — detected live, no install. You can even measure your screen's true physical size in inches.
Everything is read live in your browser — resize the window and the viewport updates.
Measure your physical screen size
Browsers can’t read your screen’s physical size, so calibrate it: hold a standard credit or bank card against the screen and drag the slider until the box below is exactly the same width. That gives your true pixel density and screen size.
Estimate — accuracy depends on matching the card width precisely and your display scaling.
Resolution vs viewport vs physical pixels
Three numbers often get confused. Screen resolution is what your display reports in CSS pixels. The viewport is the smaller area your browser draws into, after tabs and toolbars — it shrinks the instant you resize the window. And the physical resolutionis the panel's real pixel count, which equals the reported resolution times your device pixel ratio on high-density screens.
Why your numbers might surprise you
If the resolution here looks lower than your monitor's spec, it's almost always display scaling— at 125% or 150% your OS reports a smaller logical resolution so everything looks bigger, while the panel's real pixels are unchanged. Multiply by the device pixel ratio, or check the physical resolution above, to see the panel's native pixel count. Browser zoom affects the viewport and pixel ratio too, so reset it to 100% for true readings.