Paint shop pro, starting new img with right dimensions?

[gokou]

I am trying to create an image so that the rulers and grids are accurate. So if I want the grids and rulers to be 1 inch, I want it to be 1 inch in real life too.

When I mess with the ppi, it changes size, but I don't which ppi I should use to make it accurate to real life.

Thanks in advance for any help.

[the tree]

When creating a new file choose what size you want it. So long as your zoom is exactly 100% then the rulers are meant to be acurate but if your computer is using a different reslution than your screen or an annoying sibling has fidled with the proportions of your screen then they might be a bit out.