[Retric]

“One tree produces about 200 rolls (100 pounds (45 kg)).” https://en.m.wikipedia.org/wiki/Toilet_paper

Now, how much land each tree needs, and how long it takes to grow is not exactly easy to calculate. But, something like 2 * 200 trees per acre / 20 years for fast growth forest ~= 1/20 acre of forest per person for sustainable production does not sound bad.

And that’s assuming you can’t use waste streams from some other processes like sawmills.