How often to backup database and what are the favoroble practices to do so Curious to know on how often you guys back up SaaS?

I have determine that i need backups to be done every hour for an application I have, based on how often data is updated an amount of users. I have estimated that in an hour i can have about 10 new entries and about 100-200 updated entries, something on those lines, some times, at peak, it could be 2-3 times more than that.

How do you determine this number and what do you guys do?
I don't understand why you're asking this question. If you're buying in a service, then backups should be part of the SLA and not your responsibility. If it's not part of the service, then why are you using SaaS?

On the other hand, if you need to be backing up something, why are you backing up every hour?

Technically, if your application is running on a DBMS with a transaction log, it's possible to be backing up continuously, even replicating logs to (an)other machine(s). Then you have a backup process that runs regularly simply to make recovery faster (a newer backup + a small amount of logs is faster to restore than an older backup + a larger amount of logs). A retention policy on these backups and log files determines how far back in time you can go back to in case of user error (backups aren't just for when your have a "crash", they'll also be needed if someone deletes or modifies data they shouldn't have). The retention policy will often be a compromise between how far back in time you can "go" and how much space you need to store the backups + logs.