Time zone converter

How to convert a time

1. Choose the place the time is in under From.
2. Choose the place you want it converted to under To.
3. Set the date and time. The answer appears straight away.
4. Press Swap to convert in the other direction.

Why the date matters

The gap between two places is not always the same. About a third of the world's countries move their clocks forward in spring and back in autumn, and they do not all do it on the same day.

• The United States and Canada change on the second Sunday in March and the first Sunday in November.
• The United Kingdom and the European Union change on the last Sunday in March and the last Sunday in October.
• Australia and New Zealand are in the southern hemisphere, so their clocks go forward around October and back around April.
• India, China, Japan, Singapore, the Gulf states and most of Africa never change.

The result is that London is normally 5 hours ahead of New York, but for two or three weeks in March and one week in autumn it is only 4. Converting with the actual date, as this tool does, avoids being an hour out for a meeting in those weeks.

Common differences

“Summer” and “winter” here mean the northern hemisphere's daylight and standard time.

Half-hour and quarter-hour zones

Most zones are a whole number of hours from UTC, but not all. India is UTC+5:30, which is why conversions involving India always end in :30 when the other side is on the hour. Nepal is UTC+5:45, Iran is UTC+3:30, and parts of Australia are on UTC+9:30.

Arranging a call across zones

• Convert the proposed time for every person on the call, not just the organiser.
• Check the day as well as the hour. A Monday evening call in California is Tuesday morning in India.
• Write the time with the city: “3:00 PM London time”. Abbreviations such as IST and CST mean different zones in different countries.

For the two most common US conversions there are ready-made pages: PST to EST and CST to EST.

Questions

How do I convert EST to IST?

Choose Eastern Time (New York) as From and India (Kolkata) as To. India is 10 hours 30 minutes ahead of New York in winter and 9 hours 30 minutes ahead in summer.

Does the converter handle daylight saving time?

Yes. It uses the date you enter and applies whatever each place observes on that date.

Why is my result on a different day?

The two places are far enough apart that it is already tomorrow, or still yesterday, in one of them. The answer says so when the day differs.

What is UTC?

Coordinated Universal Time, the reference that every time zone is defined against. It does not change with the seasons. London is on UTC in winter and one hour ahead of it in summer.

Does IST always mean India?

No. IST is used for India Standard Time, Irish Standard Time and Israel Standard Time. Naming the city avoids the mix-up.

Last reviewed 10 October 2026.