As some may know, starting this year almost all the shipping companies started switching to a dimensional weight to calculate shipping charges instead of the actual weight.
This means to get accurate real-time shipping you need to pass the dimensions of the box you are shipping to the shipper. I'm guessing CS-Cart is not yet sophisticated enough to do this based on lack of results when I search the forum, documentation, knowledgebase, or blog, I see very little info regarding development to handle dimensional shipping rates, in fact only references I see are from this past summer saying CS-Cart doesn't handle it.
However this result does reference and input field in the import file for "box size"
http://kb.cs-cart.com/imported-fields-format
Looking at the demo of the current version I see that you can enter min-max product qty for a box size. That's a step in the right direction but is the latest version sending the box size to say, UPS, when getting a real-time quote? If not, has anyone modified the code to do so?
It would seem to get particularly tricky when ordering several different items. Obviously in many cases they can all be combined into one box and will be. To be most accurate it seems you would need the ability to enter into the system all the box sizes you use in your fulfillment. Then for each product you enter the product dimensions and either add-on room for cushioning or enter a master value for minimum cushioning to add to all product dimensions based on an additional percentage of the dimension of the product. Now you have your minimum box size for one product. It can get pretty complicated figuring out the box size for multiple different size products but it's not impossible, Amazon I'm sure does it. Even BigCommerce does it:
https://support.bigcommerce.com/articles/Public/Understanding-the-Shipping-Calculator
I can see why CS-Cart may have not wanted to invest the time in getting this sophisticated but unfortunately, now shippers are using dimensional weight calulation for all rates, it has become MUCHe important to have this type of functionality.
As it stands now, even if CS-Cart was currently using the box size to get shipping costs, based on the info I could find to this point, at best, it's going to get shipping costs assuming each product has it's own shipping box. Maybe this isn't a big concern as then if someone buys a large variety of product, the seller probably ends up charging more for shipping than it actually cost them which is a better problem then losing money on shipping. However it means that their shipping rates may be less competetive with sellers using platforms with more sophisticated/accurate shipping calculations.
I'm really surprised I couldn't find a post showing or pointing to a hack to do something like this to get more accurate dimentional weight shipping rates from some of the major shippers like UPS. It would seem like not to much work to post a PHP have for the real-time shipping function where you can edit an array setting for your box sizes. To keep things simple let's forget about box weight capacity for now. Then in CS-Cart, just set min/max per box to 1 and treat box size a product dimension with cushioning. Then modify the code to use the same forumal as BigCommerce posted, then determine which box to use and get the shipping rate. If it's a heavy item, you could purposely make the dimensions much larger than actual so it won't put too many of them in your largest box. Otherwise trying different combinations of items and box sizes while factoring in total weight of items in the box will get complicated (but not impossible.) If you go over your max box size, then you have to put the remaining items in the next box and get the rate and add to shipping total. Would just be putting a while statement around the whole thing based on a running qty count of items in box.
Without the code hack I proposed above, probably the safest things to do is to choose your min-max and box size based on the average order qty for that item. If it likely many people by 2 of them instead of almost always one, make your box size big enough to fit 2, put your max at 2, and if someone only orders one, then you make a little more money on the shipping cost versus charge differential.
Does anyone know if Big Commerce then actually has a system wide setting for all your possible shipping box dimensions and their max weight capacity?
CS-Cart: You guys need to catch up here!