How can I list my flooring products in price per sqm but sell in packs?

I am trying to set up an online flooring store and as is standard for products of this nature the prices need to be displayed per square meter. However, the products have to be sold in quantities of packs and so can't be sold specific to the square meter instead it needs to be rounded up to the nearest number of packs.

For example, if a customer wants 22sqm of a product that is sold in 5sqm packs then they will need to purchase 5 no. packs.

Other flooring websites generally have a product calculator that takes the number of sqm input and outputs the required number of packs directly in the basket.

Squarespace doesn't seem to have any kind of product calculator integration from what I can tell. Does anybody have any possible solutions or do I need to look at a different ecommerce platform that might offer this functionality?

Thank you for your time!

Would it work to sell by packs but provide an informational text that shows the total square meters?

So for example if a customer selects quantity 5 (five packs) then there would be a text blub somewhere like...

25 square meters total

Code wise that would be relatively easy, I think, to implement. I do not have any such code.

Unfortunately SS is not designed to deal with anything like square meters and the like so anything you end up doing is a bit of a hack.