What Time Zone Is Dumai In?
Dumai operates on Asia/Jakarta, abbreviated as GMT+7, which is currently UTC+07:00 from Coordinated Universal Time. The IANA Time Zone Database (also known as the tz database or zoneinfo) records this under the identifier Asia/Jakarta. That identifier is what your phone, laptop, and every major web service uses when they display a localized time for Dumai.
The designation Asia/Jakarta follows the IANA convention of naming zones after the largest city in that timezone region. This naming is geographic, not political, it reflects where the zone is observed, not which government controls it. The full record for this zone, including historical UTC offsets and past DST rule changes, is publicly available in the Wikipedia list of tz database time zones.
UTC Offset: Dumai vs. The World
The current UTC offset in Dumai is UTC+07:00. This means Dumai time is 07:00 hours ahead of Coordinated Universal Time. To quickly convert: if it's 12:00 UTC right now, it's 05:50 local time in Dumai.
Relative to other major cities: Dumai is 12 hours ahead of New York, and 7 hours ahead of London (including any DST difference currently in effect). These differences can shift by one hour during DST transitions, which occur on different dates in different regions.
Business Hours in Dumai
Standard business hours in Dumai run from 09:00 to 18:00 local time (Asia/Jakarta). In UTC, that window is 02:50 to 11:50 UTC. If you're trying to schedule a call with someone in Dumai:
- From New York: the Dumai business day runs 21:50 to 06:50 New York time.
- From London: the Dumai business day runs 02:50 to 11:50 London time.
Use the hour-by-hour conversion table above for the full 24-hour breakdown.
Daylight Saving Time in Dumai
The DST indicator above shows whether Dumai currently observes Daylight Saving Time. When DST is active, clocks advance by one hour, shifting the UTC offset by +1 and changing the abbreviation (for example, from EST to EDT in New York). When DST ends, clocks fall back and the offset returns to its standard value.
Not all countries observe DST. Japan, China, India, most of Africa, and several other nations maintain a fixed offset year-round. Whether Asia/Jakarta observes DST, and the exact dates of transitions, is governed by the rules stored in the IANA Time Zone Database , the same source your phone uses. The Wikipedia article on Daylight Saving Time provides a global map and country-by-country breakdown of DST observance.
Sunrise and Sunset in Dumai
Today in Dumai (1.7°N, 101.4°E), sunrise is approximately 06:27 and sunset is approximately 18:25 local time (Asia/Jakarta). These times are calculated using the Spencer equation for solar declination and apply to today's date. Latitude significantly affects day length: cities near the equator see roughly 12 hours of daylight year-round, while high-latitude cities experience dramatic swings, midsummer days can exceed 20 hours near the Arctic Circle, while midwinter days shrink to under 4 hours. At 1.7° latitude, Dumai's day length varies modestly across the year, the tropics maintain relatively stable day lengths.
Best Time to Call Dumai from Abroad
Standard business hours in Dumai run 09:00 to 18:00 local time (Asia/Jakarta). For international callers, the ideal window is 10:00 to 16:00 Dumai time : after the morning rush and before the end-of-day slowdown. In UTC, this translates to 03:50 to 09:50 UTC. Avoid calling before 09:00 or after 20:00 Dumai time, these windows fall outside acceptable business etiquette in most professional settings. If you are calling from New York,Dumai business hours correspond to 21:50 to 06:50 Eastern time. From London, that same window is 02:50 to 11:50 GMT/BST.
Dumai Time vs Major World Cities
Right now, Dumai (UTC+07:00) is offset from major business hubs as follows:
- New York: Dumai is 12 hours ahead of New York right now (UTC-05:00).
- London: Dumai is 7 hours ahead of London right now (UTC+00:00).
- Dubai: Dumai is 3 hours ahead of Dubai right now (UTC+04:00).
- Singapore: Dumai is 1 hour behind Singapore right now (UTC+08:00).
- Tokyo: Dumai is 2 hours behind Tokyo right now (UTC+09:00).
- Sydney: Dumai is 4 hours behind Sydney right now (UTC+11:00).
These differences shift by one hour during DST transitions, which occur on different dates in different regions. Always verify the current offset before scheduling.
Geographic Location of Dumai
Dumai sits at 1.6671°N, 101.4432°E. Solar noon, the moment the sun reaches its highest point, occurs at approximately 11:50 local time, when the sun crosses the meridian above Dumai. The IANA timezone Asia/Jakarta groups Dumai with nearby cities that share the same legal time, even if they sit at slightly different longitudes and therefore experience solar noon at slightly different moments. Zone boundaries are drawn along political borders and transportation corridors, not strict meridian lines.
Dumai: Size, Population, and Location
Dumai has a population of approximately 331,832 people, placing it among significant regional cities. The city sits at 1°40'N, 101°26'E (decimal: 1.6671°, 101.4432°),1.7 degrees north of the equator.
At 1.7° latitude, Dumai experiences relatively stable day lengths year-round, tropical latitudes see roughly 11-13 hours of daylight in all seasons, with minimal variation between the summer and winter solstice. Today, Dumai sees sunrise at 06:27 and sunset at 18:25 local time. The IANA timezone Asia/Jakarta groups Dumai with nearby cities that share the same legal clock, even if they sit at slightly different longitudes with marginally different solar noon times.
Working Hours Overlap: Dumai and Key Partners
Dumai's standard working day (09:00–18:00 local, Asia/Jakarta) translates to different hours for common international partners:
- San Francisco (America/Los_Angeles): Dumai's workday runs 18:50 to 03:50 Pacific time.
- Berlin (Europe/Berlin): Dumai's workday runs 03:50 to 12:50 Central European time.
Overlap windows, times when both cities are within 09:00–18:00, are the practical window for real-time collaboration. Use the time difference tool on this site to find the shared working window for any pair of cities.