Convert times between 33 world time zones. World clock, business hours overlap, 24/12-hour format, and quick pairs for major city routes.
Working across time zones is a daily reality for remote teams, international businesses, travelers, and anyone scheduling calls or meetings with people in other countries. The world spans 38 time zones (including half-hour and quarter-hour offsets), and mentally calculating the time difference while accounting for AM/PM, date changes, and daylight saving time is error-prone and frustrating.
This converter supports 33 time zones from UTC-12 to UTC+13 (including the half-hour and quarter-hour offsets used by India, Iran, Nepal, Newfoundland, and others). It shows the converted time in both 24-hour and 12-hour (AM/PM) format, calculates the business hours overlap window for scheduling meetings, provides a world clock showing eight major time zones simultaneously, and flags date-line crossings.
Quick-pair presets for common international routes (NYC→London, LA→Tokyo, NYC→Mumbai) let you start conversions instantly. For anyone coordinating across borders, this tool eliminates the guesswork and timezone.com tabs that accumulate during international scheduling. Check the example with realistic values before reporting.
Mental timezone math fails when you are crossing the date line, accounting for half-hour offsets, or estimating overlap windows. This tool shows the conversion, world clock, and business overlap in one view — no tab-switching required. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
Destination time = Source time + (destination UTC offset − source UTC offset) If result < 0: subtract 1 day and add 24 hours If result ≥ 24: add 1 day and subtract 24 hours
Result: 04:00 AM (+1 day)
UTC offset difference: +9 − (−5) = +14 hours. 14:00 + 14 = 28:00 = 04:00 next day. A 2 PM call in New York is 4 AM the next day in Tokyo.
About 70 countries observe DST, shifting clocks forward 1 hour in spring and back in fall. The US, Canada, and most of Europe observe DST from March to November (Northern Hemisphere). Australia and New Zealand observe it from October to April (Southern Hemisphere). Countries near the equator generally do not observe DST.
- **UTC+5:45 (Nepal)** is the only major timezone with a :45 offset - **UTC+13 and UTC+14** exist because Samoa and Kiribati jumped across the date line in 2011 and 1995 respectively to align with their trading partners - **China** uses a single timezone (Beijing Time, UTC+8) despite spanning ~5,200 km east-west — equivalent to the width of the continental US, which uses 4 time zones - **Antarctica** has no standard timezone; each research station uses the timezone of its supply country
| Route | Difference | Best overlap (source time) | |---|---|---| | NYC → London | +5 h | 9 AM – 12 PM | | LA → Tokyo | +17 h | 4 PM – 6 PM | | NYC → Mumbai | +10:30 h | 8 AM – 9:30 AM | | London → Sydney | +10 h (winter) | 7 AM – 8 AM | | Berlin → SF | −9 h | 3 PM – 6 PM |
Coordinated Universal Time (UTC) is the primary time standard. It is essentially the same as GMT (Greenwich Mean Time) but defined by atomic clocks. All time zones are expressed as offsets from UTC.
India (UTC+5:30), Iran (UTC+3:30), Nepal (UTC+5:45), and others use non-hour offsets. These reflect historical, geographical, or political decisions — India spans 2,500 km east-west but uses a single timezone at the midpoint.
This converter uses standard (winter) UTC offsets. During daylight saving time (summer), many zones shift +1 hour (e.g., EST→EDT, GMT→BST). Adjust manually or verify current offsets.
The IDL runs roughly along the 180° meridian in the Pacific. Crossing it westward adds a day; eastward subtracts a day. Some countries near the line (Samoa, Tonga) use UTC+13, placing them ahead of UTC+12 by one full day.
The converter calculated the overlap between 9 AM–5 PM in both time zones. If the overlap is zero, one party must meet outside normal hours.
There are 38 distinct UTC offsets in use, from UTC-12 to UTC+14. Most are whole hours, but several use :30 or :45 offsets.