To find your screen resolution, open a resolution checker and read the headline figure. The free screen resolution tool shows your resolution in pixels along with your window size, device pixel ratio, colour depth and aspect ratio, and it updates live as you resize the window or move it to another monitor.
That covers the quick answer. The part that confuses most people is why the number they see does not match the box their screen came in, so let us clear that up.
Why your resolution might look “wrong”
Buy a phone advertised at 2532 by 1170 pixels and a resolution checker may report something like 844 by 390. Nothing is broken. Modern screens are high-density, and the browser reports the logical resolution, which is the physical resolution divided by the device pixel ratio.
So a phone with a pixel ratio of 3 reports a third of its physical width and height. Multiply the logical numbers by the pixel ratio and you get back to the figure on the box. The tool shows both the logical resolution and the calculated physical pixels so you do not have to do the maths.
What each number means
Screen resolution
The total pixels your whole display has, width by height. This is the figure people usually mean by “resolution”.
Browser window
The size of the area the page can actually use right now. If the browser is not maximised, this is smaller than the screen. Designers and developers care about this one, because it is what a layout responds to.
Device pixel ratio
How many physical pixels sit behind one CSS pixel. A ratio above 1 means a high-density screen, which is why text and images look crisp.
Colour depth and aspect ratio
Colour depth is the bits used per pixel, which sets how many colours the screen can show. Aspect ratio is the shape of the screen, such as 16:9 or 16:10, simplified from the resolution.
When you need these numbers
- Support tickets. Help desks often ask for your exact resolution and pixel ratio. Read them straight off the page.
- Design and development. You design against the viewport size and pixel ratio, not the raw resolution, especially on retina screens.
- Checking a new monitor. Confirm the screen is running at its native resolution rather than a lower fallback the system picked.
If you are checking a new monitor, it is worth pairing this with the refresh rate test to confirm the screen is also running at its full hertz, and the dead pixel test to check the panel itself.