Hanoi is 5 hours ahead of Bucharest
Best overlap: 8:00 AM to 1:00 PM in Bucharest is 1:00 PM to 6:00 PM in Hanoi.
The hours that work for both Bucharest and Hanoi are 8:00 AM to 1:00 PM (Bucharest) and 1:00 PM to 6:00 PM (Hanoi). Hanoi is 5 hours ahead of Bucharest, leaving about 5 hours of shared hours — plan recurring calls early in that window to leave buffer. A quick caveat — Bucharest's clocks move for daylight saving and Hanoi's don't, so the times here are right for only part of the year.