How Time Zones Work
The world is divided into time zones — regions that observe the same standard time. Most are defined as an offset from UTC (Coordinated Universal Time). UTC+0 is the baseline; zones to the east are ahead (positive offsets) and zones to the west are behind (negative offsets). For example, New York is UTC−5 in winter, and Tokyo is UTC+9 year-round.
Daylight Saving Time (DST) shifts clocks forward one hour in spring and back in autumn in many countries, temporarily changing their UTC offset. Not all countries observe DST — Japan, China, India, and most of Africa do not — so the offset difference between two cities can change depending on the time of year. This converter uses the browser's built-in Intl.DateTimeFormat API, which automatically applies the correct DST rules for any given date.
Understanding the Meeting Planner
The meeting planner shows 5 suggested times at the source location and their equivalents in the target zone. Each time slot is colour-coded by business-hours overlap: green (both cities in 9 AM–6 PM), amber (one city in business hours), and red (neither city in business hours). This makes it easy to find a slot that works for both parties without manually cross-referencing two calendars.
Frequently Asked Questions
Intl.DateTimeFormat API with IANA timezone identifiers, which automatically applies the correct DST rules for every location and date. The DST badge on each zone card shows whether DST is currently active.Intl.DateTimeFormat().resolvedOptions().timeZone value — the IANA timezone identifier derived from your system settings. No GPS or network location request is made. It then matches that identifier against the zone list and pre-fills the From field.People Also Search For
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