This depends on the match between what you are seeking and what Hanoi has to offer. For example, if you want to see more scenic places, you may opt to go to Halong Bay or Sapa from Hanoi, and either of this will take up at least 2 days of your time already. If you want to stay within Hanoi and visit places of interest, maybe 4 days will be sufficient. If you are the type to take things slow, you can easily fill 6 days.
Thank you for your reply! Ya I like to take things slow, planning to go to halong bay and sapa, after that what are the interesting places to visit in hanoi? never been there before..

