M.P.
Depends on how often you do laundry and whether or not you're going to reuse the towels or napkins before washing them. Also what are you using the towels for. What are they made of? Since you say unpaper, I'm guessing they aren't a woven fabric.
I use my dish cloth for one day and wipe up any spills that happen on the counters, table, stove with that one cloth. I have a stack of old terry towels in my kitchen on a counter that I use for messes on the floor. I go thru 7-10 dish clothes and probably 1-3 old terry towels in a week. I usually rinse out the terry towel and use it again. I only do laundry every couple of weeks. That means I need 14-20 dish cloths and 2-4 terry towels, tho in reality I don't wash the terry towels every time I do laundry.
I do use nice looking terry kitchen towels for drying my hands and dish towels for drying dishes. I change the terry towels every day and the dish towel, which seldom gets used, every week.
As for cloth napkins, we use the same ones over all week long. Each person has their napkin. For 4 people I'd need 8 napkins. However, I like to use different colors and patterns and so I probably have two or three dozen napkins or more in sets of 4 that I've collected over the years. Periodically I go thru them and donate ones I haven't used in a year.
I made my Christmas napkins out of wash and wear fabric in a red and green plaid. I think it has some polyester along with cotton in it because they wash and dry nicely without needing to be ironed and yet absorb well. 100% cotton absorbs more and most of my napkins are that. I don't mind a few wrinkles and so don't iron them. I have some linen napkins which I do have to iron and so seldom use them. Synthetic fabrics do not absorb well and make poor napkins.