CDT 対 EST — 違いは？
CDT と EST は UTC −5 を共有しますが、異なるゾーンに属します：中部（夏）対東部（冬）。
CDT (Central Daylight Time) and EST (Eastern Standard Time) actually share the same UTC offset of −5:00. The catch is that they're never in active use at the same time:
- CDT is used by Chicago/Houston/Dallas during the summer DST window.
- EST is used by New York/Atlanta/Miami during the winter (when DST is not in effect).
While CDT is active in summer, U.S. Eastern is using EDT (Eastern Daylight Time, UTC −4) — which is one hour ahead of CDT.
| Comparison | CDT | EST |
|---|---|---|
| UTC offset | UTC −5 | UTC −5 |
| Used in season | Summer | Winter |
| Cities | Chicago, Houston, Dallas | New York, Atlanta, Miami |
| Sister zone | CST (UTC −6) winter | EDT (UTC −4) summer |
Practical answer
When people ask "what's the difference between CDT and EST?" they almost always mean: "how many hours behind is U.S. Central from U.S. Eastern right now?" The answer is always 1 hour — Central is one hour behind Eastern, regardless of whether it's CDT/EDT (summer) or CST/EST (winter).
Try the CDT → EST converter for a live 24-hour table.