Cost-calculation regarding write operations

[SteveHeller]

Dear all

I need to calculate the monthly costs of my Azure object storage and I find it especially difficult to calculate the costs of the write operations.
As far as my research goes I found that 1 operation equals about 1 MB of data transfered to Azure.

Now how does that go with Synthetic Full backups?
I'd like to go with daily incremental backups with one synthetic full once a week.
Can I calculate the estimated transfered data for the synthetic full? Will it equal the size of a full backup or rather the size of an incremental backup (as it is synthetic full)?

How about GFS archival backups? These are basically just retention flags so it should not need to transfer any data, correct?

Thank you for your help.

[Gostev]

Our object storage integration is incremental forever, so only deltas are uploaded always, regardless of how the particular restore point is stored on-prem. Thanks!