Timezone Converter

How the Timezone Converter Works

Enter the time you want to convert, select the source timezone, then select the destination timezone. The tool calculates the UTC offset difference between the two zones using the browser's built-in Intl.DateTimeFormat API — no external API calls needed.

Your local timezone is detected automatically. The current time in each timezone is shown so you can quickly verify the results. Use the Swap button to reverse the conversion direction.

Understanding Time Zones

Time zones were established in 1884 at the International Meridian Conference in Washington, DC, with representatives from 25 nations. Before that, every city set its own local time based on the sun — fine when travel was slow, but a nightmare once railroads started connecting cities. A traveller crossing the United States might need to adjust their watch dozens of times. The conference divided the Earth into 24 one-hour zones anchored to the Prime Meridian through Greenwich, England.

In practice, there are more than 37 time zones — not 24 — because politics and practicality pushed many regions to adopt non-standard offsets. India uses UTC+5:30 to cover the entire subcontinent in one zone. Nepal uses UTC+5:45. The Chatham Islands of New Zealand use UTC+12:45. China spans five natural time zones but uses a single one (UTC+8) for national unity. Daylight Saving Time makes it even messier: not all countries observe it, and those that do switch on different dates — the US and Europe are about two weeks apart — so the offset between two cities can shift twice a year.

Tips for Working Across Time Zones

Remote work and global teams have made time zone awareness a daily skill. These habits reduce errors and protect your teammates' off-hours.

• Use UTC as your common reference. When coordinating across multiple zones, say "3:00 PM UTC" instead of asking each person to convert from your local time. UTC never observes Daylight Saving Time, making it a stable anchor that eliminates ambiguity during DST transitions when local times shift unexpectedly.
• Schedule meetings in the overlap window. For US–Europe teams, the overlap between business hours is typically 4–6 hours (morning US East Coast / afternoon Europe). For Asia–Europe, the overlap can be as narrow as 1–2 hours. Mapping this window explicitly at the start of a project prevents the recurring friction of finding meeting times.
• Use a world clock or converter tool — don't do mental math. Time zone arithmetic seems simple but is surprisingly error-prone, especially across DST transitions or when a city is on the other side of midnight. A quick check with a converter takes seconds and avoids the embarrassment of scheduling a call at the wrong time.
• Be aware of DST transition dates. The US switches on the second Sunday of March and first Sunday of November. Most of Europe switches the last Sunday of March and October — roughly two weeks after the US in spring, two weeks before in autumn. During those two-week gaps, offsets between US and European cities shift by one hour from their usual values.
• Respect "core hours" boundaries. Scheduling a call at 7:00 AM or 10:00 PM for a remote colleague signals disregard for their personal time, even if the request seems urgent. Establishing explicit core hours (e.g., 9 AM–5 PM local time for each team member) and protecting them for scheduling creates sustainable working conditions across distributed teams.

Built for distributed teams

The old version converted one time between two zones. Useful, but you'd immediately open three more tabs to check the same meeting time for three other cities. Now you can pin up to six cities side by side and drag the time slider — every column updates at once. The 50-city autocomplete covers the cities that actually come up in distributed work: Nairobi, Karachi, Lagos, not just New York and London. DST is handled automatically by the browser's Intl API, so you don't need to remember which countries switched last week.

Your city set saves between visits. Reload the page next week and the same six cities are waiting. We considered adding calendar integration and shareable links — both got cut. A shareable link sounds useful until you realize the recipient needs to know what time zone they're in anyway, and calendar apps already handle that. What we kept: the slider. Typing a time to see how it lands across cities is slower than just dragging.

Frequently Asked Questions