A Timezone Guide So You Stop Miscalculating Meeting Times

Daylight saving time changing on different dates in different countries is what actually causes the confusion.

Summary

The time difference between two cities isn't fixed — because countries switch to daylight saving on different dates, the gap between the same two cities can be 7 hours for part of the year and 8 hours for another part. It's safer to rely on a tool that uses current timezone rules than to calculate it by hand.

Step by step

When planning a meeting, enter both your city and the other person's city into a timezone converter.
Communicate the result in the other person's local time, not in your own time converted for them.
During daylight saving transition weeks (around March and November), double-check the calculation the day before.
For cities you meet with often, jot the result down, but re-verify it each time rather than trusting memory.

Why it matters

You usually find out about a timezone mistake when it's already too late. The other person waited on the call an hour ago, or you're sitting alone in an empty meeting room. It sounds like a minor slip, but with a client call, a job interview or an exam, it can cost you the outcome. One detail many people miss: some countries don't observe daylight saving at all. Turkey, for example, stays on UTC+3 all year. So the gap between Istanbul and London or New York only shifts when the other side changes its clocks, and it's on you to keep track.

Common mistakes

Writing the timezone as an abbreviation. EST, CST and IST are used for more than one region; IST can mean India or Ireland. A city name is safer.
Assuming Europe and the US change clocks on the same day. They don't. For a few weeks each spring and autumn, even the London to New York gap is different from usual.
Not checking the date for meetings that cross midnight. Tuesday evening for you is Wednesday morning for someone in East Asia.
Creating a calendar invite without a timezone. Some calendars save it as floating time and show every attendee the same clock number in their own local time.
Checking a recurring meeting once and trusting it for months. After a daylight saving switch, the whole series can drift by an hour.

A realistic scenario

A team in Istanbul meets partners in Berlin and New York every Monday. All winter the slot works for everyone. In March, the US moves its clocks forward while Europe hasn't yet, and the New York team shows up an hour early. A few weeks later Germany switches too, and the gaps change again. From then on, the team pins the invite to Istanbul time and sends a short heads-up to everyone during the spring and autumn transition weeks.

What to put in the invite

The clearest approach is to write the time twice: the other person's local time first, then yours in brackets with a city name. For example, 'Thursday 10:00 New York time (Istanbul 17:00)'. For meetings with many attendees, adding the UTC time helps everyone do their own math. Make sure the invite itself has the right timezone selected. When the text and the invite disagree, most people trust the invite.