@CStyles - The board cover image appears to be related to the aspect ratio rather than dimensions. The cover images are 1:1 (or square).

However, to answer the question of dimensions, they appear to display at 190x190 pixels.

@CStyles - And after opening the Developer tools console tools in Chrome, it looks like perhaps the images are stored as 160x160:

Hi, I think an image is stored with its own size and scaled automatically when it is displayed according to your own resolution. And when it is displayed the result depends on more the ratio of it. How I checked the ratio on the dashboard is not 1:1(square). I pinned a picture to show the ratio.

Ahhh, so it appears as 1:1 in most cases except for grid view.

Dashboard List view:

Grid view:

If I take this 160x160 square:

And use it as a cover and view it in grid mode it is 290x302:

List mode it is 45x45 (square):

And Board details view it is 190x190:

I guess whatever cover image you use, give yourself some space around it.

yeah, how I get it. An image is centered in the middle.And the ratio is almost 1:1. Use any square picture. The pieces cut off I think are not seen with an ordinary view.