Work out inter region transfer cost instantly with clear inputs, formula shown and shareable results.
Inter-region transfer is cheaper than internet egress but multiplies with replica count: replicating to two regions doubles the bill. Compression is applied before transfer, so it reduces the charge in direct proportion — a three-to-one ratio cuts two thirds of the cost, which is why replication protocols that compress on the wire matter financially as well as operationally.
Inter-region cost
compressed TB = data / compression ratio; total = compressed x replica regions; cost = total x 1000 x price per GB
Usually only egress from the source region is charged, but some services bill both directions. Check the specific service's pricing rather than assuming.
Compress and deduplicate before transfer, replicate only what must be regional, and consider asynchronous replication of deltas rather than full snapshots.