Timezone Difference
Calculate the hour difference between any two time zones.
13h
Tokyo 13h ahead
New York
UTC-4:00
Tokyo
UTC+9:00
How It Works
- 1
Select two timezones
Choose a source and target timezone from the searchable dropdown. You can search by city name, country, or IANA zone identifier.
- 2
View the difference
The calculator displays the exact hour and minute offset between the two zones for today's date, including DST status for both. A timeline visualization shows the relationship clearly.
- 3
Check other dates
Change the date to see how the difference varies throughout the year due to DST transitions. The calculator highlights dates when the offset changes.
Understanding Time Zone Differences
The Timezone Difference calculator shows you the exact hour and minute offset between any two timezones, accounting for Daylight Saving Time on both sides. While many people know that New York is "5 hours behind London," this is only true for part of the year — during the weeks when the US and UK switch to DST on different dates, the difference temporarily becomes 4 hours. Our calculator eliminates this guesswork by computing the precise offset for any specific date. It draws on the IANA Time Zone Database, which tracks the full history of UTC offset changes for every timezone, including the transitions caused by DST. The tool displays the difference in both directions (e.g., Tokyo is UTC+9, Los Angeles is UTC-8, so Tokyo is 17 hours ahead of Los Angeles), making it clear which city is ahead. Beyond simple offset math, the calculator shows whether either timezone is currently observing DST, when the next DST transition will occur for each zone, and how the difference will change at that point. This is particularly valuable for recurring international meetings and deadlines: a 3:00 PM EST deadline translates to different UTC times depending on whether EST or EDT is in effect. The calculator supports all IANA zones including unusual offsets like UTC+5:30 (India), UTC+5:45 (Nepal), and UTC+13 (Tonga), ensuring accurate results for even the most uncommon timezone pairs.
Frequently Asked Questions
Why does the time difference between two cities change during the year?
Most time difference changes are caused by Daylight Saving Time. If two cities observe DST on different dates — or if one observes it and the other does not — their offset shifts temporarily. For example, the US and EU switch clocks on different weekends, creating a brief period each spring and autumn when the usual difference changes by one hour.
Can two cities have a non-whole-hour difference?
Yes. Several timezones use half-hour or even quarter-hour offsets. For instance, the difference between London (UTC+0 or UTC+1) and Mumbai (UTC+5:30) is always 5 hours 30 minutes or 4 hours 30 minutes, depending on British Summer Time.
What is the largest possible time difference between two places?
The maximum difference is 26 hours, between UTC-12 (Baker Island) and UTC+14 (Line Islands, Kiribati). In practice, the most common large difference is about 17-18 hours, between US West Coast and East Asia or Oceania timezones.