Scheduling with India without rounding away the half hour

India’s civil clock is UTC+5:30. It does not change for daylight saving. Every meeting with Mumbai, Delhi, or Bangalore lands on the half hour, and the most common bug is a helpful person who moves it to the hour because the :30 looked like a typo.

If you remember one check, it is this: a time with India that lands on the hour is the thing to distrust, not the time that lands on :30. The history of why the offset is a half hour, along with Nepal’s :45 and Newfoundland, is in half-hour and 45-minute time zones. This article is about the invite in front of you.

London

London and Mumbai are four and a half hours apart while London is on British Summer Time, and five and a half hours while London is on standard time. Summer time runs from the last Sunday of March to the last Sunday of October.

9:00 AM in London is 1:30 PM in Mumbai during summer time, and 2:30 PM in Mumbai during the winter. It is not 1:00, and it is not 2:00. A 4:00 PM London call is 8:30 PM or 9:30 PM in Mumbai, which is why teams that work this corridor a lot stay in London’s morning. Anything before London’s lunch is a fair Mumbai afternoon. Anything after it is an evening ask, and it gets an hour later in the winter without anyone editing a London-anchored invite.

Mumbai keeps the same clock. London is the side that moves. If the hard stop is “not after 7:00 PM Mumbai,” anchor the event to Mumbai. London will see its hour change twice a year, which is the change London already expects from every other international series. The invite ownership guide is the general version of that choice.

New York

Mumbai and New York are 9 hours 30 minutes apart from the second Sunday of March to the first Sunday of November, and 10 hours 30 minutes the rest of the year. “About 10 hours” is never the right number. It is an hour wrong in one season and half an hour wrong in the other, and the half hour is still there in both.

The workable band is New York’s early morning against Mumbai’s evening. 8:30 AM in New York is 6:00 PM in Mumbai during the 9h 30m setting, and 7:00 PM during the 10h 30m setting. A 9:00 AM start in Mumbai is 11:30 PM the previous night in New York in the long summer, and 10:30 PM in the winter. The friendlier arrangement, if New York will take it, is a 7:00 AM call, which buys Mumbai a late afternoon instead of an evening. Somebody is outside 9-to-6 either way. Say which side, and keep it for the quarter instead of alternating until both sides are annoyed.

A recurring New York morning call, pinned to New York, moves an hour later for Mumbai on the first Sunday of November and an hour earlier on the second Sunday of March. The :30 rides along. People notice the hour and forget that it was never on the hour to begin with.

Singapore and Dubai

Mumbai and Singapore are the calm version. Singapore is two and a half hours ahead, all year, and neither city changes clocks. 9:00 AM in Mumbai is 11:30 AM in Singapore. 3:00 PM in Mumbai is 5:30 PM in Singapore. 6:00 PM in Singapore is 3:30 PM in Mumbai, still inside a normal Mumbai afternoon. There is no reason to push this pair into the evening. The overlap is most of the day. Use it.

Dubai and Mumbai are an hour and a half, also all year. 9:00 AM in Dubai is 10:30 AM in Mumbai. The flight is a little over three hours, which is close enough to the clock gap that people joke about it and then send the invite at 10:00. The weekends line up for most companies, because the UAE moved to Saturday and Sunday in 2022. The calendars that do not line up are religious. Ramadan shortens a lot of Dubai days. Diwali and Holi move Indian ones. Neither list is a substitute for the other.

The invite habit

Put the :30 in the title as well as in the time field. “Mumbai 1:30 PM / London 9:00 AM” survives a colleague who recreates the event from memory. A title that says “India sync” does not.

Do not maintain a personal offset table for this. The pair pages read the IANA zone, which is Asia/Kolkata for the whole country. India, like China, keeps one civil clock across a wide map. A colleague in Kolkata and a colleague in Mumbai are on the same hour. If your tool shows otherwise, the tool has the wrong zone, not a secret second Indian time.

The limit: a 9-to-6 grid will call a lot of London-morning slots “good” and say nothing about a Mumbai team that starts later, or about a holiday you did not enter. The grid is the shape of the day. The holiday list is still your job. For teams that also have a third city with no overlap, the rotation problem is the remote team scheduling guide, not a sharper offset.