oh goodness i have spent way too much time trying to figure this out. and here i find this. but i spent so much time trying to figure it out bc i was like there is no way not to be able to add dimensions. Lampshades weigh like 3lbs IF that, but bc of the box size, can cost $30+ and $30 is cheap with my UPS biz account. this is wack. kickbacks perhaps? im shocked.
Also realized you can bulk edit dimensions and variants by downloading the products CSV, editing and reuploading it:
It is not only bizarre but absolutely crazy that Shopify, an Ecommerce platform where shipping is imperative, would not have the capability to record dimensions for shipping... what?? It's impossible to get accurate rates without that piece. Seems to me that all it would take is the addition of one field to the product page. It can't be that hard, and it appears that you have several VERY frustrated customers Shopify... add it please!! The fact that we have to pay for an app to include such basic information is maddening.