Time Zone Calculator Online Free

Time Zone Calculator

Convert time between timezones worldwide with daylight saving time support. World clock, international meeting planner, and travel schedule calculator. Covers all IANA timezone database entries including UTC offsets and DST transitions.

Time Zone Concept

Target Time = Source Time ± Zone Difference

Variables:

UTCCoordinated Universal Time (reference)
Coordinated Universal Time (reference)(e.g.: UTC+0)
ESTEastern Standard Time
Eastern Standard Time(e.g.: UTC-5)
PSTPacific Standard Time
Pacific Standard Time(e.g.: UTC-8)
CETCentral European Time
Central European Time(e.g.: UTC+1)
DSTDaylight Saving Time
Daylight Saving Time(e.g.: +1 hour (summer))

How to Use the KalkuLab Time Zone Converter

1
Select Source Time Zone
Choose the source time zone or city.
2
Enter Time
Input the date and time to convert.
3
Select Target Time Zone
Choose the destination time zone or city.
4
View Result
The converted time in the target zone is displayed.

Examples

Jakarta to New York

Problem:

Meeting at 9:00 AM WIB (Jakarta). What time is it in New York (EST)?

Solution:

1.WIB = UTC+7
2.EST = UTC-5
3.Difference = 7 - (-5) = 12 hours
4.9:00 AM WIB = 9:00 - 12 = 9:00 PM (previous day)

Result:9:00 PM EST (previous day)

When it's morning in Jakarta, New York is still the previous evening.

Tokyo to London

Problem:

Event at 8:00 PM JST (Tokyo). What time is it in London (GMT)?

Solution:

1.JST = UTC+9
2.GMT = UTC+0
3.Difference = 9 hours
4.8:00 PM JST - 9 hours = 11:00 AM GMT

Result:11:00 AM GMT

Tokyo is 9 hours ahead of London.

Frequently Asked Questions

What is UTC?

UTC (Coordinated Universal Time) is the world's primary time standard, practically the same as GMT. All time zones are expressed relative to UTC (e.g., UTC+7 for Western Indonesia Time).

What is Daylight Saving Time?

DST is the practice of advancing clocks by one hour during summer to make better use of daylight. It is used in Europe, the US, and Australia. Indonesia does not use DST.

Why does Indonesia have 3 time zones?

Indonesia spans about 5,000 km east to west, covering roughly 47° of longitude. Three zones (WIB, WITA, WIT) accommodate the geographic difference in solar time.

Which countries differ most from Indonesia?

From WIB (UTC+7), the farthest difference is UTC-12 (Baker Island) = 19 hours behind, or UTC+14 (Line Islands, Kiribati) = 7 hours ahead but on a different calendar date.