Timezone Converter
Pick a date/time and two cities to see the matching local time.
Why do time zones exist?
Time zones exist because the Earth rotates, meaning different parts of the world experience daylight at different moments. Rather than everyone using one global clock, each region sets local time roughly aligned with the sun's position, so "noon" stays close to midday. This creates the need to convert times when scheduling calls or meetings across regions.
Why time zone boundaries aren't straight lines
In theory the world could be divided into 24 neat vertical slices, one per hour — but real time zone boundaries bend around country borders, and a handful of zones sit at unusual 30- or 45-minute offsets (India, Iran, and parts of Australia among them) rather than a full hour. Political decisions, not just geography, shape where a boundary falls: China spans a distance that would naturally cover five time zones but uses a single official time nationwide, which is why the math can surprise people who assume time zones map cleanly onto longitude.
Frequently Asked Questions
Why does the time difference sometimes change between two cities?
This is usually caused by daylight saving time (DST). Many countries in Europe and North America move clocks forward in spring and back in autumn, but not every country observes DST, and they don't all switch on the same dates. So the gap between two cities can shift by an hour depending on the time of year.
Is UTC the same as GMT?
For most everyday purposes, yes — UTC (Coordinated Universal Time) and GMT (Greenwich Mean Time) refer to the same baseline time. Technically UTC is the modern scientific standard while GMT is a time zone name, but in practice they line up and are used interchangeably outside of specialist contexts.
How do I schedule a meeting that works for multiple time zones?
Pick a reference time zone (often the organizer's), convert it to each participant's local time using a tool like this one, and look for a window where the meeting falls within reasonable working hours everywhere. Late morning in Europe often overlaps well with early morning on the US East Coast, for example.
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Good for scheduling calls
Pick the date and time as it would appear in the "from" city, then choose the "to" city to see the equivalent local time there. Handy for planning meetings, calls, or flights across regions without doing the math by hand.