The gap between New York and Bangkok is 12 hours for 127 days of the year and 11 hours for the other 238. That flip comes from one place only: New York. ICT stays locked at UTC+7. EST is fixed at UTC−5. But New York abandons EST for EDT (UTC−4) from the second Sunday of March through the first Sunday of November, and that single clock change rewrites every schedule between the two cities.
Why the EST to ICT gap is 12 hours, not 11
Add the offsets. EST sits at UTC−5. ICT sits at UTC+7. The distance between them is exactly 12 hours. When it is 09:00 in New York on a January morning, it is 21:00 in Bangkok the same day. No date flip, no ambiguity.
That 12-hour spread holds only while New York stays on standard time. From 08 March 2026 through 31 October 2026, New York runs on EDT (UTC−4). The gap shrinks to 11 hours. A 09:00 New York start in July lands at 20:00 in Bangkok.
When does the EST to ICT gap change?
Two dates control the shift in 2026. On Sunday 08 March at 02:00 local, New York springs forward to EDT. The gap narrows from 12 hours to 11 hours overnight. It stays at 11 hours through the summer. On Sunday 01 November at 02:00, New York falls back to EST, and the 12-hour gap returns for the rest of the year.
In 2027 the pattern repeats: forward on 14 March, back on 07 November. Bangkok never moves. ICT is fixed at UTC+7 every day of the year, so the entire swing comes from New York’s daylight schedule.
Working hours between EST and ICT never overlap
Whether the gap is 11 hours or 12 hours, a standard 09:00 to 17:00 workday in New York and the same window in Bangkok do not touch. At 09:00 Monday in New York, it is 21:00 Monday in Bangkok. When Bangkok starts work, New York is deep in the night.
Do not hunt for a same-day meeting slot. It does not exist. The only model that works is a handoff: finish your day, send the work, and the other side picks it up when they start. A 09:00 New York call means a 21:00 Bangkok call in winter, or 20:00 in summer. That can work as a one-off if one team takes a late evening, but it is a stretch for a recurring sync.
Does “EST” mean the same thing everywhere?
No. EST also stands for Australian Eastern Standard Time, which is UTC+10. If someone in Sydney says “EST,” they mean a zone 15 hours ahead of New York’s EST. Always confirm which EST is in play when a conversation crosses the Pacific. ICT carries no such risk: it only ever means Indochina Time.
The practical rule for this pair: use the 12-hour gap only from November through early March. For the rest of the year, use 11 hours. And when you book anything, assume zero overlap and plan for an asynchronous handoff.
Before you convert, check whether New York is displaying EDT or EST. If it says EDT, the gap is 11. If it says EST, the gap is 12. That single check kills every scheduling error.