Instantly see your screen resolution, browser viewport size, pixel ratio, aspect ratio and color depth. Updates live as you resize the window.
Screen resolution is your full display in CSS pixels. Multiply by the pixel ratio for the true hardware pixels (a 2x Retina display reports half its physical width here). The viewport is the part of the page your browser can draw in right now.
Screen resolution is the full size of your display in CSS pixels. The viewport is the smaller area inside the browser window where the page is actually drawn, after toolbars and tabs are subtracted.
Browsers report sizes in CSS pixels, not hardware pixels. On a high-DPI or Retina display the device pixel ratio is 2 or 3, so a 2560-pixel-wide panel may report as 1280. Multiply by the pixel ratio for the physical resolution.
Yes. The viewport, orientation and aspect ratio update live as you resize the window or rotate your device.
No. Everything is read from your browser locally and nothing is uploaded.