While live shipping rates are only available for manual orders, Shopify Advanced Plan users, WooCommerce plugin users, and API users, only flat rates can be set for your Big Cartel store.
To correctly set the shipping settings on your Big Cartel store, we suggest following Big Cartel's guide on shipping settings. You can see our shipping flat rates on our Shipping page.
P.S. - Printful doesn't ship to Iran, Cuba and North Korea.