9am in Chicago is 11pm in Seoul

Seoul is 14 hours ahead of Chicago. Chicago runs on America/Chicago (UTC-5); Seoul runs on Asia/Seoul (UTC+9). The difference is measured right now; it can shift by one hour during daylight-saving-time transitions.

Chicago observes daylight saving time — shifting between CST (UTC-6) and CDT (UTC-5) — while Seoul stays on KST (UTC+9) year-round. The difference is 15 hours in Chicago’s winter and 14 hours in Chicago’s summer. Transitions happen in late March and late October for most Northern-Hemisphere DST zones, and late September/early April for Southern-Hemisphere ones — check the current date against the city’s DST schedule before anchoring a meeting at the edge of those windows.

Standard 9-to-5 business hours in Chicago and Seoul do not overlap. Teams operating across this pair either stretch their schedules — an early-morning call from the westward city lands as an evening call in the eastward one — or rely fully on asynchronous tools. Scheduled windows at the edges (first thing for one side, last thing for the other) are the usual compromise, with one side absorbing the unsocial-hours cost this week and the other side next week.

When planning recurring meetings across Chicago and Seoul, pin them to one city’s local time rather than UTC or the other city’s clock. That way, the meeting time stays stable for the person anchoring the schedule, and the other side absorbs the one-hour drift during DST transitions. The alternative — a meeting pinned to the non-DST city — means the DST city sees the meeting time “move” twice a year, which is how recurring calendar invites end up at 7am on someone’s calendar in October.