I live in Mumbai and work with people in the US and Europe, so I schedule across seven to ten and a half hours most weeks. Here’s the method I use. It takes about five minutes and it removes almost every “wait, is that your morning or mine?” message.

1. List everyone's city, not their time zone

Write down the city each person is in. Cities carry the daylight saving rules; abbreviations like CST are ambiguous (US Central or China Standard).

“EST” is a good example: people use it all year, but New York is actually on EDT (UTC−4) from March to November. If you schedule by city, the rules come along for free.

2. Find the working-hours overlap

Line up each person's 9-to-5. The overlap is the window where nobody is asked to work early or late.

Some pairs overlap comfortably: London and New York share about three hours (9:00 AM–12:00 PM in New York). Some barely touch: San Francisco and Bengaluru have no 9-to-5 overlap at all, so one side is always early or late.

This is the step Time Zone Pro was built for. Add everyone’s city, drag one slider, and stop when every card says Working. On Android, Find a time colours each person’s day and lets you drag one meeting window across all of them.

3. If there's no overlap, rotate who is inconvenienced

Alternate between an early slot for one side and a late slot for the other, instead of always asking the same people.

For a weekly US–India call, that might mean 8:30 AM in New York (6:00 PM in Mumbai) one week and 9:30 PM in New York (7:00 AM next day in Mumbai) the next. Fair beats convenient for the person sending the invite.

4. Check the daylight saving weeks

In March and October/November the US and Europe change clocks on different weekends. Recheck recurring meetings around those dates.

The full list of dates is in daylight saving time dates. India, China, Japan, Singapore and the Gulf don’t change at all, so the gap with them moves whenever the other side changes.

5. Write the time in every attendee's zone

Put both times in the invite, for example 9:00 AM New York / 6:30 PM Mumbai, so nobody converts in their head.

Calendar apps convert automatically for attendees, but people still read the description, the Slack message and the email. Writing both times costs ten characters and saves a missed meeting.

Quick reference

EST to IST: India is 9½ hours ahead in US summer, 10½ in US winter.
London to New York: 5 hours behind, 4 for a few weeks in March and October/November.
PST to IST: India is 12½ or 13½ hours ahead; there’s no working-hours overlap.
CET to IST: India is 3½ or 4½ hours ahead; a comfortable morning-in-Europe window.