About monitor resolution

Your monitor’s resolution is described in pixel dimensions. For example, if your monitor resolution is set to 1600 x 1200 and your photo’s pixel dimensions are the same size, at 100%, the photo will fill the screen. The size an image appears on‑screen depends on a combination of factors: the pixel dimensions of the image, the monitor size, and the monitor resolution setting. In Photoshop Elements, you can change the image magnification on‑screen, so you can easily work with images of any pixel dimensions.

A 620 x 400‑pixel image displayed on monitors of various sizes and resolutions

When preparing images for on-screen viewing, you should consider the lowest monitor resolution that your photo is likely to be viewed on.

  This page on the Web