Time zone guides.
Worked examples for converting local times, understanding clock changes, and choosing meeting dates across countries.
Choose the guide for your question
If you have two cities and a date, start with how to convert time zones. It walks through UTC-offset arithmetic, including half-hour differences. If your result lands tomorrow or yesterday, the calendar-date guide explains what to write in an invitation and how to handle midnight.
For a recurring transatlantic call, use the 2026 New York–London clock-change reference. For other cities, compare the actual date in the converter and consult the clock-change calendar.
Daylight saving time explained
Why clocks change, why countries change on different dates, and how to keep your meetings on track.
Read guideUTC vs GMT: what is the difference?
Two familiar names, one useful reference. Understand UTC, GMT, and what an offset actually means.
Read guideHow to schedule across time zones
A practical guide to shared working hours, respectful scheduling, and meetings that survive clock changes.
Read guideEST, PST, IST and other time zone abbreviations
Learn when abbreviations mean a fixed offset, when they are ambiguous, and why city names prevent mistakes.
Read guide12-hour and 24-hour time explained
Make sense of am, pm, midnight, and the 24-hour clock, with simple examples you can use immediately.
Read guideHow to convert time zones: worked examples
Calculate the time difference using UTC offsets, including half-hour zones, seasonal changes, and dates that cross midnight.
Read guideWhen New York and London are four hours apart in 2026
See when a 09:00 New York meeting becomes 13:00 in London in 2026, with exact dates for the spring and autumn clock-change gaps.
Read guideNext day or previous day? Time zone date changes explained
Read +1 day and −1 day indicators, calculate overnight examples, and write midnight appointments with an unambiguous date and city.
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