To calculate how many hours until 3:00, I need to know whether you mean 3:00 AM or 3:00 PM. Since the current time is 5:29 AM EDT on May 23, 2025, here are both possibilities:

• Until 3:00 AM (next day):
  From 5:29 AM today to 3:00 AM tomorrow is 21 hours and 31 minutes.

• Until 3:00 PM (today):
  From 5:29 AM to 3:00 PM today is 9 hours and 31 minutes.

Please let me know which 3:00 you mean, or if you want it in a different time zone!