Combined items postage help!

[StinkingEelPie]

If you combine two items for postage - does eBay calculate the new postage cost?
I find it easy on Vinted but this has got me flummoxed!
any tips and guidance massively appreciated - thanks

It can depend ……

As a seller I list postage in different ways, which may be ‘free postage’ taken into account against the full price, which may be because it’s a cheap item or to make my listing potentially more attractive than another seller of a similar item, or by a specified postage price.
If I have shown ‘free postage’ then eBay has nothing to combine and I’ll keep the extra by sending in one package

But if I have listed a postage rate then I would combine. If a buyer pays for an item then buys another then they end up paying both of the postage amounts - I would then make a partial refund equating to the ‘over payment’
A few times when I’ve had a buyer after multiple items I have told them not to pay until I produced an eBay invoice in which I adjusted the postage - but that was mostly with a lot of items, therefore I may have needed to use a heavier / bigger postage option which cost more than the listed rate but a lot less than multiples added up

I think that there isn’t an auto combination by eBay for seller listed rates, as it could come up with the wrong answer.

eBay simplified postage is / should be a different matter, as the seller specifies the size & weight but eBay charge a price and provide the label/QR code.
I have used it deliberately a few times, and on others I have missed that eBay reverted to that setting.
I have sold multiples once with eBay simplified involved with 3 items. Two large items were on simplified and the third small one was my postage. They buyer paid the full cost for all of the postage, and I could not then combine them. (I don’t know if they paid for the two one at a time or if it just didn’t combine anything)
So I sent three separate packages, whereas they would all have been fine on the one large rate

Thank you so much- that’s really detailed and helpful. Much appreciated