Convert IST (India Standard Time) to CDT (Central Daylight Time)

Which IST is this?

IST names more than one zone. This page reads it as India Standard Time at UTC+5:30, which is the reading most converters take. There are others: Israel Standard Time at UTC+2, used in Israel in winter; Irish Standard Time at UTC+1, used in Ireland in summer.

The letters on a meeting invitation do not say which one is meant. If yours is not India Standard Time, the answer above is wrong, and not by a little:

Any converter has to pick one of these readings before it can answer, and two of them can pick differently — a page of search results for a IST conversion can show you both answers with neither being wrong. The one to trust is whichever states the zone it means rather than only the letters. Where it matters, ask which country the sender is in.

Best time to schedule a meeting

Standard 9–5 working hours do not overlap at all between IST and CDT. Someone has to take an early or late call — or use asynchronous communication instead.

IST to CDT conversion table

About IST

India Standard Time (IST) is UTC+5:30. It is used in all of India and Sri Lanka, on a half-hour offset.

India Standard Time is UTC+5:30 — one of the handful of zones offset by half an hour, which breaks any code that assumes whole-hour offsets and any mental arithmetic that does the same. India has no daylight saving and one time zone for the entire country, despite spanning nearly 30 degrees of longitude. The abbreviation is also used for Irish Standard Time and Israel Standard Time, both of which are entirely different offsets.

About CDT

Central Daylight Time (CDT) is UTC−5. It is used in Chicago, Dallas and Houston from March to November.

Central Daylight Time is UTC−5, the summer clock for Chicago, Dallas and Houston, from the second Sunday in March to the first Sunday in November. Mexico is the complication: it abolished daylight saving nationally in 2022, so Mexico City stays on UTC−6 all year and is now an hour behind Chicago for eight months of the year rather than matching it.

Does this gap change with the seasons?

This gap is seasonal. The abbreviations themselves are fixed offsets, but the region on CDT switches to CST (UTC−6) from November to March. So the 10.5-hour figure on this page is correct for the part of the year when both places are actually on these abbreviations, and changes by an hour outside it.

IST does not shift, so the whole change comes from one side. A recurring meeting fixed in IST will appear to move by an hour for everyone on the other side, twice a year, without anyone changing anything.

This is the reason scheduling systems store an IANA zone such as Region/City rather than an offset or an abbreviation: the zone knows its own rules and the offset does not.

Frequently asked questions