South Korea and US Time Difference: Best Times to Call Seoul

Last updated November 3, 2026 · Written by Han with AI assistance, fact-checked against official sources.

South Korea keeps one clock all year, so every change in the gap comes from the US side.

Compare New York and Seoul on a date of your choice in the Meeting Planner.

Seoul against every US time zone

The table is calculated from the time zone database for 2026. January shows US standard time and July shows US daylight saving time. Phoenix and Honolulu do not change their clocks, so their gap to Seoul is the same all year.

The middle column is the start of the Korean work week. When Seoul opens on Monday morning, the whole US is still on Sunday, from Sunday afternoon in Honolulu to Sunday evening in New York. The last column counts the hours when both cities are inside a 9 a.m. to 5 p.m. day. Only Honolulu, Anchorage and, in winter, Los Angeles get any.

The two dates the gap changes

US daylight saving time starts on the second Sunday in March and ends on the first Sunday in November. On those dates the gap to Seoul moves by one hour, and nothing changes in Korea. The next change is on Sunday, March 14, 2027, when US clocks spring forward.

A call fixed in Seoul time moves for the US side. A 9 a.m. Seoul meeting is at 7 p.m. the evening before in New York in winter and 8 p.m. in summer. A call fixed in New York time moves for the Seoul side instead. Choose the city that owns the meeting time and name it in the invite. The guide to recurring meetings and clock changes shows how calendar apps handle this.

Seoul is already on tomorrow

At noon on a Wednesday in New York, it is 2 a.m. on Thursday in Seoul in winter and 1 a.m. in summer. From 10 a.m. in New York in winter, or 11 a.m. in summer, until midnight, Seoul is on the next day. On the West Coast that starts at 7 a.m. in winter and 8 a.m. in summer.

• A US Friday afternoon is a Korean Saturday morning. A 5 p.m. Friday call from New York lands at 7 a.m. Saturday in Seoul in winter and 6 a.m. in summer.
• A Seoul Monday morning is a US Sunday evening. If you need an answer from Seoul on Monday, send the question before your weekend starts.
• Deadlines need a city. "End of day Friday" in Seoul means 5 p.m. Friday there, which is 3 a.m. Friday in New York in winter and 4 a.m. in summer.

Best times to call South Korea from the US

New York and Seoul never share an hour of the 9-to-5 day, so one side has to stretch. From the East Coast, 7 to 9 p.m. reaches Seoul at 9 to 11 a.m. in winter and 8 to 10 a.m. in summer. From the West Coast, 4 to 6 p.m. reaches Seoul at the same hours, so a Los Angeles caller can use the end of the office day.

Honolulu does best. Hawaii is 19 hours behind Seoul all year, so 2 to 5 p.m. in Honolulu is 9 a.m. to noon the next day in Seoul, inside both working days.

For calls to family, the Seoul evening works too. 8 to 10 p.m. in Seoul is 6 to 8 a.m. in New York in winter and 7 to 9 a.m. in summer, before most American workdays start.

Korea's clock since the 1950s

Korea has changed its standard time more than once. The time zone database shows Seoul on UTC+8:30 from March 1954, set by the 127.5 degrees east meridian that runs through the peninsula, and back on UTC+9 from August 1961. The Standard Time Act now fixes the standard meridian at 135 degrees east, the same one Japan uses, so Seoul and Tokyo always show the same time. Japan and US Time Difference has the Tokyo tables, including Japanese holidays in US time.

Korea used summer time in several years from the late 1940s, including most of the 1950s. The National Archives of Korea records that it came back in 1987 and 1988, ahead of the Seoul Olympics, and was dropped after that. In the time zone database, the 1988 period ran from May 8 to October 9. The Standard Time Act still lets a presidential decree adjust the clock for part of the year, so a return would need only a decree, not a new law.

KST and the US codes

Korea Standard Time is written KST. It has no summer version in use today, so a Korean invite that says KST means UTC+9 in any month. On the US side, EST and PST are only correct in winter. In an invite between the two countries, write "Seoul time" or "UTC+9" next to the US city, and put both dates.

Quick checks before you book

• Write both dates, not just both times: "Tuesday 7 p.m. New York / Wednesday 9 a.m. Seoul".
• Check the week after the second Sunday in March and the first Sunday in November. Those are the weeks when a fixed call shifts by an hour on one side.
• Arizona outside the Navajo Nation and Hawaii keep the same gap to Seoul all year, so a Phoenix and Seoul team can keep one schedule.

Open the Meeting Planner to test a time, or see the city pages for Seoul, New York, Los Angeles and Honolulu. The Asia and Pacific time zones guide covers Korea's neighbors, Philippines and US Time Difference works through the same problem for Manila, and China and US Time Difference does it for Beijing.