Setting India Time Zone on Your Devices

Why your meeting alarm fired an hour late

India has not moved its clocks since 1971. The offset is fixed at UTC+5:30, year-round, no daylight saving. If your device applies DST rules to India, every event you schedule shifts. The official IANA zone is Asia/Kolkata. It was renamed from Asia/Calcutta in 2008. If you search for "Asia/New_Delhi" in any time zone picker, you will not find it. That entry does not exist in the IANA database.

India's IANA zone: Asia/Kolkata

Every operating system and calendar service uses the IANA time zone database. For India, the single entry is Asia/Kolkata. Some systems display a city name instead of the IANA key. On Windows you might see "Kolkata" or "Chennai" depending on your version. Both map to the same zone and both produce IST at UTC+5:30. The city name is cosmetic. The offset and rule set are identical.

Set the zone on Windows

1. Open Settings (Windows key + I).
2. Go to Time & Language > Date & Time.
3. Turn off "Set time zone automatically" if it is on.
4. Click the time zone dropdown. Type "Kolkata" or scroll to UTC+05:30.
5. Select Kolkata (UTC+05:30).

What can go wrong: Older Windows computers may have an outdated time zone database. If you see "Chennai" instead of "Kolkata", select it. It is the same zone. If you see "Asia/Calcutta", select it. That is the old name for the same zone. If you see "New Delhi" as a listed city, do not select it. Windows may have added it as a display alias, but it is not the IANA key. Stick with Kolkata or Chennai.

Set the zone on Mac

1. Open System Settings.
2. Go to Time & Language (or Date & Time on older macOS).
3. Turn off "Set time zone automatically" if you need to override it.
4. Click the time zone map or search "Kolkata".
5. Select Kolkata from the list.

What can go wrong: macOS uses the IANA database directly. If you type "Delhi" into the search box, nothing appears. You must type "Kolkata". If your Mac is set to automatic and it picks the wrong zone, check your location services are enabled in System Settings > Privacy & Security > Location Services.

Set the zone on iPhone and iPad

1. Open Settings.
2. Tap General > Date & Time.
3. Turn off Set Automatically.
4. Tap Time Zone and search "Kolkata".
5. Select Asia/Kolkata.

What can go wrong: iPhone may show "India Standard Time" as a label with Kolkata underneath. That is correct. If you have automatic time zone enabled and it picks a zone based on your network location (for example, if your carrier routes through a foreign server), you may see the wrong offset. Turn off automatic and set it manually.

Set the zone on Android

1. Open Settings.
2. Go to Date & Time (or System > Date & Time on some Android versions).
3. Turn off Automatic time zone.
4. Tap Time Zone and search "Kolkata".
5. Select Asia/Kolkata or India Standard Time (UTC+5:30).

What can go wrong: Android's list sometimes shows "New Delhi" as a searchable alias. Selecting it works, but the underlying zone is still the correct one. If you travel internationally and your phone switches to local time, the meeting times in your calendar will shift. Keep automatic off if you need IST while abroad.

Set the zone in Google Calendar

Google Calendar uses your device or browser time zone, but you can set a secondary time zone.

1. Open Google Calendar in a browser.
2. Click the gear icon (top right) > Settings.
3. Under Time zone, select India Standard Time (UTC+5:30).
4. To show a second time zone, go to Time zone > Show secondary time zone and choose Kolkata (IST).

What can go wrong: Google Calendar abbreviates India Standard Time as "IST", but so does Israel Standard Time (UTC+2) and Irish Standard Time (UTC+1 in summer). If you invite someone and their calendar resolves "IST" to the wrong zone, your meeting time shifts. Always verify the offset in the event details. Google shows the UTC offset next to the zone name. If it says "IST (UTC+5:30)", it is India. If it says "IST (UTC+2)", it is Israel.

Why does my clock show the wrong IST offset?

The clock is off by one hour. Your device probably applied daylight saving time. India has no DST. Go back to the time zone settings and make sure you selected a zone that does not have DST rules. The correct zone has no DST. If you accidentally selected "Asia/Tehran" or "Asia/Jerusalem", those zones do observe DST. The fix: reselect the correct zone.

The clock is off by 30 minutes. You selected a zone with a different half-hour offset, such as Asia/Kathmandu (UTC+5:45) or Asia/Colombo (historically UTC+5:30 but Sri Lanka changed in 2006). Verify you have the zone mapped to UTC+5:30.

The clock shows the correct time but calendar events are wrong. Your calendar may be using a different time zone than your device. In Google Calendar, check the event time zone settings. In Apple Calendar, check the calendar's time zone override under Edit > Time Zone.

Why did my time zone name change from Calcutta?

The IANA database renamed Asia/Calcutta to Asia/Kolkata in 2008. The change was cosmetic. The offset and rules are identical. If a device or piece of software still shows "Asia/Calcutta", treat it as the correct India zone. If you see both, prefer the newer name.

Quick reference checklist