Question DPI, resolution, pixels per inch, creating a wallpaper for dual monitors


Aug 7, 2018
So I have a 22" widescreen monitor connected to my Windows 7 laptop (via VGA) which I use as an extended desktop. I noticed that by default Windows will use the same wallpaper that my laptop screen (15.6") uses, which of course ends up not filling the entire display.

So fix this, I decide to use Photoshop to just stitch together the 2 different wallpaper images I want to use. I just added the Widths and heights of my display resolutions (1366x768 and 1680x1050) which btw are both displays' native resolutions. The combined size is 3046 x 1818 in my case ..

But I do not know if I need to change the default Resolution (PPI) to a value specific to the combined height/width of my dual displays?

I mean, when I am using Photoshop and sometimes I need the ruler to be accurate so I just use an online tool to calculate the proper PPI based on screen resolution and diagonal size. However, dealing with dual displays is new territory for me...

Here are a couple of screen caps to clarify my question

1. Photoshop new image values, width/height are correct and the Resolution shown is Photoshop default

2. Based on results from the tool on this website I found on google, the Resolution of 100.45 PPI
is what I always use whenever I am using photoshop on my laptop and need an accurate ruler for my current task

Thank you and sorry if my question or way of asking is rather convoluted, it's hard for me to explain kinda