Grace period prior to domain ending up in Redemption varies and it may be different for each domain extension.
For .COM and .COM.SG, the grace period is usually 29 days, after which it will go in to redemption period for 30 days.
If domain is still not renewed by then, it will be deleted and open to public for registration.
Redemption fee is costly and should be avoided as it is usually domain registration fee plus administrative cost which may be more than the domain fee itself.
Also, if your site is popular or consist of good key phrases, it will be nearly impossible to register it once it is deleted as it may be snapped up almost immediately by others once available.
