How do I accurately calculate shipping when offering more than one of the same item?

[antis]

I have 8 of the exact same item to sell. For this reason, in the Sell an Item form I've indicated I've set the Quantity to 8 and I've chosen Buy It Now and turned off auction or accept offers. I know the size and weight to ship one of them. I can't offer free shipping or a flat cost. But it looks like when a Buyer indicates they want to buy more than one, the calculated shipping cost is only changing based on weight and zone, but not package dimensions. Experimenting with the shipping cost part of the listing, I know that shipping two of these items in one box means bigger dimensions, and that really changes the calculated cost. But the Checkout experience seems to only care about weight and zone. It's not like I can fit all 8 of these into one box - each additional item a Buyer wants means a bigger box, which is a higher cost, but it's not showing that in the checkout. How do I accurately get the right calculated cost to the Buyer before they buy? Ideally, I'd be able to pack what they want, measure and weigh the package, then generate an invoice. But doesn't Buy It Now require immediate payment? I really don't know what to do. THANKS in advance!

[fern*wood]

No offense, but how often does dimensional shipping enter the picture for your multi sold items?  With shipping, size definitely matters and is more than nickels & dimes when you combine items of size.  All methods do not work for all sellers.

[rfmtm]

@antis  Yes, and this is what many sellers do and most buyers understand how to put items in their cart and ask for a total.  Plus this method gives the most accurate results.

While turning off the immediate or advanced payment method does open you up  to some non-paying buyers, this is usually from buyers making Best Offers, which you are not using.

[bashort]

What I have done with flat rate boxes that will only fit one widget is set the weight where 2 will be over the weight limit and then the calculator will charge the FL cost for each item.

I used to do this a lot when I used a lot of regional boxes, I would put the weight of the item based on how many of the widgets would fit in the box.

Then to test log into a different account and put them in the cart and see what the shipping charge is