Haha, the number depends on sweater size. My largest bag is 16"x19" and I can probably fit 5 light sweaters/knit tanks in it. I bought a set of bags like this one online and I love them!

Am I right that these mesh things are what I'm looking for in terms of washing? Also, do you think it would be better to wash alone or with some blankets and stuff? Seems like other stuff in the wash would provide some padding, but also something to rub against

Nice. How much do they hold?

I bought these https://smile.amazon.com/gp/product/B01D58R1BE/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 and the large size holds 3 gallons (two 6-qt shoeboxes) and the smaller just over 6 quarts.

When washing and drying put it in a fine mesh laundry bag so it doesn’t rub against other clothes as much. 6 Pack - SimpleHouseware Laundry Bra Lingerie Mesh Wash Bag (3 Large & 3 Medium) https://www.amazon.com/dp/B01D58R1BE/ref=cm_sw_r_cp_api_i_9jEvCbWKCFB49