Image size for web.

I have general question, what size of images you found work better for PNet?

I look at my images on different displays, and quite often, they don't look the way I want you see them.

Sometimes they may be OK on my 4K display, but look like s....t on other screens. I tried different sizes and resolutions, but seems there's no direct correlation beet image size and how it looks on the web.

If PNet does some resizing, reprocessing behind the scene, we probably should know basic standards.

Something like "keep size of your images under 1000 pix" doesn't qualify, because sometimes they look OK, sometimes not, even with the same pixel sizes.

For example: Squarespace creates up to seven versions of that image, each with a different width.Squarespace's built-in responsive design picks the appropriate image size based on the visitor's screen.

What sizes PNet use?