Step 1. Think in UTC offsets, but name cities
Every time zone is an offset from Coordinated Universal Time (UTC): Baku is UTC+4, Moscow UTC+3, New York UTC−5 in winter and UTC−4 in summer. Offsets are what you calculate with, but cities are what you should communicate, because a city’s offset can change during the year while its name does not. Converters and calendars use the IANA time zone database (names like Europe/Berlin), which records each region’s rules, including DST history.
Step 2. Find the overlap in working hours
- Open the time zone converter, set the date of the meeting (the date matters — see DST below) and add every participant’s city.
- Look for hours that fall inside 9:00–18:00 for everyone; the tool highlights them.
- If there is no full overlap, rotate the inconvenient slot between regions instead of always asking the same people to join late.
Example for a winter date: 14:00 in Berlin (UTC+1) is 08:00 in New York (UTC−5) and 17:00 in Baku (UTC+4) — a narrow but workable window for all three.
Step 3. Watch out for daylight saving time
DST is the main source of scheduling mistakes, because countries switch on different dates — and many don’t switch at all.
| Region | Clocks go forward | Clocks go back | 2026 dates |
|---|---|---|---|
| US and Canada (most areas) | 2nd Sunday of March | 1st Sunday of November | 8 Mar / 1 Nov |
| EU and UK | Last Sunday of March | Last Sunday of October | 29 Mar / 25 Oct |
| Southeastern Australia | 1st Sunday of October | 1st Sunday of April | 4 Oct / 5 Apr |
| Russia, Azerbaijan, Kazakhstan, Turkey, UAE, India, China, Japan | No DST — same offset all year | ||
What this means in practice:
- The “shoulder weeks”. Between 8 and 29 March 2026, and between 25 October and 1 November 2026, the US and Europe are out of sync. A New York–London gap that is normally 5 hours becomes 4.
- Countries without DST drift twice a year. Baku–Berlin is 3 hours in winter and 2 in summer; Baku–New York is 9 hours in winter and 8 in summer.
- Seasons are reversed in the southern hemisphere. When Europe moves clocks forward in spring, Sydney moves them back for its autumn, so the Europe–Sydney gap can change by two hours across a few weeks.
- Missing and repeated hours. On the spring-forward night in the US, local times from 2:00 to 2:59 do not exist; on the fall-back night, 1:00–1:59 happens twice. Avoid scheduling automated jobs in those windows.
Step 4. Write the time so nobody misreads it
- Send a calendar invite. Google Calendar, Outlook and others store the event in absolute time and show it in each person’s zone.
- In text, anchor to UTC or cities: “Tue 3 Nov, 15:00 UTC — 10:00 New York, 16:00 Berlin, 19:00 Baku”.
- Avoid ambiguous abbreviations. CST can mean US Central or China Standard Time; IST can be India, Ireland or Israel. “EST” is only correct in winter.
- Use 24-hour time in international messages to avoid AM/PM confusion.
- For developers: store timestamps in UTC and convert for display; ISO 8601 with an offset (
2026-11-03T15:00:00Z) is unambiguous. See also our Unix timestamp guide.
Recurring meetings
A weekly meeting is pinned to the organiser’s time zone. When the organiser’s country changes clocks, everyone elsewhere sees the meeting move by an hour — or the reverse. Put a reminder in your calendar for the last week of March and the end of October to check every cross-border series, and agree in advance whose local time is the anchor.
Quick checklist
- Check the offsets for the meeting date, not today.
- Find the 9–18 overlap; rotate unsociable slots fairly.
- Send an invite; in text, give UTC plus cities.
- Re-check recurring meetings in late March and late October/early November.
Frequently asked questions
Why did the time difference with my colleagues change by an hour?
Because daylight saving time (DST) starts and ends on different dates in different countries — or not at all. For example, the US switches on the second Sunday of March and the EU on the last Sunday of March, so for two or three weeks the New York–London gap is 4 hours instead of 5.
Which countries do not use daylight saving time?
Many, including Russia, Azerbaijan, Kazakhstan, Turkey, the UAE, India, China and Japan. Their UTC offset stays the same all year, so the difference with Europe or North America changes twice a year.
Should I write EST or EDT?
EST is UTC−5 (winter) and EDT is UTC−4 (summer). Writing “EST” in July is technically wrong. Safer: name a city (“10:00 New York time”) or give the UTC time.
What is the best way to send a meeting time?
Send a calendar invitation — calendar apps convert it to each participant’s local time automatically. In plain text, give the time with a city or UTC offset, e.g. “3 Nov, 15:00 UTC (10:00 New York, 19:00 Baku)”.
What happens to a recurring meeting after a clock change?
It stays at the organiser’s local time. For participants in places that changed clocks on a different date (or not at all), the meeting moves by an hour. Review recurring cross-border meetings around late March and late October/early November.