Best time to call
Seoul is 13 hours ahead of New York. Here are the call windows that respect both your day in New York (United States) and theirs in Seoul (South Korea), plus the daylight saving and holiday traps to watch.
9 AM New York
= 10 PM Seoul
9 AM in New York = 10 PM in Seoul, comfortable for you but outside their working day, so agree it in advance.
8 PM New York
= 9 AM Seoul
8 PM in New York = 9 AM in Seoul, inside their hours but early or late for you, so it is your sacrifice to make.
9 PM New York
= 10 AM Seoul
9 PM in New York = 10 AM in Seoul, inside their hours but early or late for you, so it is your sacrifice to make.
Watch out for these
Both cities are loaded with New York as the anchor. Adjust the day or hours to see the overlap shift, including around daylight saving transitions.
Sorted by participants in business hours
Green = inside 9:00–17:00
Seoul is 13 hours ahead of New York. From your desk in New York, that means your morning is already their afternoon, and the window where both teams are at their desks is narrower than it looks. The cleanest single slot is 9 AM your time, which lands at 10 PM in Seoul.
With a gap this wide, there is almost no natural overlap between a 9-to-5 in New York and a 9-to-5 in Seoul. One side has to stretch. The honest move is to decide in advance whose comfort you are trading away, then rotate it so the same team is not always taking the early or late call. Do not pretend a painless slot exists; it usually does not at this distance.
The recommended slots above are computed against today's offset, which is the safe default. The trap is the twice-a-year daylight saving changeover: New York and Seoul do not necessarily move their clocks on the same weekend, so for a few weeks each spring and autumn the gap can shift by an hour and every recurring invite quietly misfires. If your call is near a transition date, confirm the exact wall-clock time on both ends rather than trusting the difference.
On these dates both United States and South Korea are likely off, so do not schedule.