Please check out the price calculated for 80GB storage 16gb RAM for 3 node replica set in atlas vs documentdb
The below price comparison given in mongodb official site doesn't make sense to me
you can see the calculations i have done in AWS pricingcalculator and in mongodb atlas pricing calculator in the attached snapshots
which is cheaper DOCUMENTDB or MONGODB ?
I see that document DB doesn't charge for backups and data transfer between replicas but Mongodb atlas charges 0.01/GB for same region and 0.02/GB for diff region even for data transfer between replica nodes