Commerce: Postage by weight for multiple purchases

[Meddysong]

I'm looking to go live with my site in a few days' time and I've just hit a potential niggle.

I know I can define shipping rates and I can do so by weight. But it's dawned on me that if a user purchases several different items, then the total postage they pay at the end might be summation of the postage weight applied to each individual item. If item A bought on its own is $2, B $3, C $4 and D $5, then a customer buying all four would be charged (A + B + C + D) $14, even though the cost of such a package might actually be $6.

That could be very problematic for us. I don't think anybody would expect to buy three books and pay such large postage. (For reference, we're in the UK and our postage is calculated in tiers by weight. It's quite possible to have three of something fall into the same weight range as one of those things.)

Am I right? Is that how Commerce works? If I am, is there a solution? Is it possible to set something up such that the postage paid depends on the total weight of the package and isn't individually summed from the components?

[opentype]

4 minutes ago, Meddysong said:

Am I right? Is that how Commerce works? 

No. You can set global weight tiers, so it’s not added shipping costs per product, but by overall weight. 

[Meddysong]

That's really reassuring, Ralf -- thanks. When I find the time, I'll need to do some experiment I think to make sure I get it working correctly.