Bless your heart, Ma and Pa.......I will try to help you, for I am a vintage seller.
I posted this the other day:
****I sell vintage, and much of it is glassware 2 pounds and over. I hope that what I am going to share will help other vintage sellers. I know some sellers are having a difficult time with calculated shipping (CS), but I am one of the lucky ones, my shop works wonderfully with it. So please take what I am sharing and use it if you are able, if it doesn't work for your shop, then just disregard it and find another possible solution. I can only share what works for MY shop, it may not be feasible for yours. And I can say....I simply love it!
I primarily use two boxes: USPS Priority Mail 7 x 7 x 6 and USPS Priority Mail 12 x 12 x 8. I have put these two boxes in the "Package Preferences" area. I will eventually add USPS Flat Rate boxes to these preferences.
My item dimensions are already in my listings, so for each listing I look at the item and add packaging to those dimensions. I use plenty of bubble wrap, and I use styrofoam plates and bowls to wrap glassware in as feasible. I simply take all of this into consideration when I come up with the final dimensions to put in the listing.
An example: a plate that is 8" in diameter........
I put 10 x 10 x 3 as the dimensions in the listing. I do this because I enclose that plate within styrofoam plates and bubble wrap. Granted, it will not be 3 inches in height, but I allow a little extra space because I simply do not like to pack items tightly in a box, I allow plenty of extra space between items so I can use newspaper or whatever in between them. This also helps the calculator to not put too many items in a box.
The calculator will then use the 12 x 12 x 8 box, it will bypass the 7 x 7 x 6 box.
On weight, I use item weight and box with packaging....in other words, I use the weight of the complete package when it is ready to ship. This has been easy for me, because thankfully, I have always added the weight of the item and the weight of the final package to the bottom of each listing.
A teacup and saucer will fit in a 7 x 7 x 6 box. A saucer is usually around 5 1/2" in diameter, and a teacup is around 3 1/2" or so. I use something like 6 x 6 x 5 or whatever to accommodate the bubble wrap, styrofoam, etc. The calculator will then put this item in a 7 x 7 x 6 box.
If a customer orders a teacup and saucer that will fit into a 7 x 7 x 6 box, and then orders a serving plate with a handle on top that has the dimensions with packaging at 10 x 10 x 6, the calculator will put the serving plate in the box that is 12 x 12 x 8, and the teacup in the 7 x 7 x 6 box, as it should be.
So if shipping on the serving plate is $7.55 (retail rate on east coast - I live in Georgia), and shipping on the teacup and saucer is $5.95 (retail rate on east coast), then it will calculate correctly at $13.50. And the order will ship in 2 boxes.******
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Okay, Ma and Pa, I have since added on 3 more Priority Mail boxes.....small flat rate, medium flat rate, large flat rate. No now I use the following sizes:
a. 7 x 7 x 6 small priority box
b. 12 x 12 x 8 large priority box
c. small flat rate 8 5/8 x 5 3/8 x 1 5/8
d. medium flat rate 11 x 8 1/2 x 5 1/2
e. large flat rate 12 x 12 x 5 1/2
Item dimensions need to be item wrapped with packaging. Weight needs to be that plus the box.....the total weight the package will be when taken to the post office.
I've kind of developed a system, because even though I sell vintage, a lot of my item dimensions are going to be repetitious. Teacups and saucers will usually have close dimensions. Sugar and cream sets will have much the same dimensions, plates and casseroles and pitchers and salt and pepper shakers have similar dimensions, so my system is:
medium flat rate box......i usually use the dimensions of 10 x 8 x 5
large flat rate box........i usually use the dimensions of 10 x 10 x 5
small flat rate box......i usually use the dimensions of 4 x 4 x 2 or 5 x 3 x 2
large priority box......i usually use the dimensions of 10 x 10 x 6
small priority box.......I usually use the dimensions of 6 x 6 x 4 or 6 x 6 x 5
The above are simply dimensions I use a lot, for a lot of my items generally have the same dimensions, and gradually you will notice a pattern in item dimensions developing, as I have. Yes, they do vary and I take that into consideration.
Really, all I do is decide what box they will fit in and then put the dimensions in the item listing that I need to make that item fit in the box. Basically, I just tell Mr. Calculator what to do :)
It is super simple for me, and it works dandy in my shop.
Well, this is a lot to read through, but maybe it will help. My best to you!