I'd like to knock out a few prints for friends and family and am looking for some advice on the size and resolution I need to be working at to give me a a print of 'wall-hangable' size (maybe 8 inches square).

I currently work at 600px square, but converting px to inches seems to be far more confusing than I imagined.

Any and all advice very welcome.

let me start with this: printing is a difficult topic.

the kind of quality you can get depends strongly upon how much effort you are willing to put in.

First of all, printers usually work in the CMYK "color space" (i.e. each dot on the paper has its color mixed from a portion of cyan, a portion of magenta, a portion of yellow, and a portion of black), whereas screens work in the RGB color space (where pixels are made up of a red portion, a green portion, and a blue portion).

If you want your colors to come out right, you'll want to think about color management, which is a set of tools that try to make sure that the print will look like the image looked on your screen when you were working on it.

For that to work properly, you first need a color profile of your screen. This is more difficult than you might think, because every single monitor on the planet has slightly different color characteristics. Only extremely expensive monitors are properly calibrated. You can buy or borrow a colorimeter to measure your monitor's output and create a color profile for your computer (windows and krita) to use.

After that you will need to obtain a color profile of the printer that will be used to print out your piece of art. This is usually a bit easier to come by, because professional print shops know all about that stuff and they can probably just send you the .icc file that fits the printer you're going to get.

However, that's not what you were asking for.

Resolution is another important piece of the puzzle. Obviously, if you work in a low resolution, it'll come out blurry on paper.

Converting from inches to pixels is easy, since the common measurement for printing resolution is "Dots Per Inch" aka DPI.

If you have 8" x 8" at 300 dpi, you'll end up with a 2400x2400px image. I think 300 dpi is a common size and should be acceptable, but maybe you want to try printing out some test pictures on a common paper size and see how fine lines and individual pixels will become. Krita comes with a few presets, like "A4 (300 dpi)", and you can use these for that very purpose.

I hope all of this could help you a little bit, and not just give you more trouble …

300 dpi is mostly fine for colored images; for line art that is really black and white (i.e., not gray), 600dpi is the most used resolution.

If your image is 600 pixels by 600 pixels, its printed size at 300 dpi would be 2 by 2 inches.