Time Zone Converter — Convert Time Between Time Zones
Convert any date and time between world time zones instantly. See also Military Time Converter and Countdown Timer.
Current Time in Major Cities
| City | Time Zone | Current Time (12h) | Current Time (24h) | UTC Offset |
|---|---|---|---|---|
| UTC | UTC | 12:07:21 PM | 12:07:21 | UTC+0 |
| New York | America/New_York | 8:07:21 AM | 08:07:21 | UTC-4 |
| Chicago | America/Chicago | 7:07:21 AM | 07:07:21 | UTC-5 |
| Denver | America/Denver | 6:07:21 AM | 06:07:21 | UTC-6 |
| Los Angeles | America/Los_Angeles | 5:07:21 AM | 05:07:21 | UTC-7 |
| London | Europe/London | 1:07:21 PM | 13:07:21 | UTC+1 |
| Paris | Europe/Paris | 2:07:21 PM | 14:07:21 | UTC+2 |
| Berlin | Europe/Berlin | 2:07:21 PM | 14:07:21 | UTC+2 |
| Tokyo | Asia/Tokyo | 9:07:21 PM | 21:07:21 | UTC+9 |
| Shanghai | Asia/Shanghai | 8:07:21 PM | 20:07:21 | UTC+8 |
| Kolkata | Asia/Kolkata | 5:37:21 PM | 17:37:21 | UTC+5.5 |
| Dubai | Asia/Dubai | 4:07:21 PM | 16:07:21 | UTC+4 |
| Sydney | Australia/Sydney | 10:07:21 PM | 22:07:21 | UTC+10 |
| Auckland | Pacific/Auckland | 12:07:21 AM | 00:07:21 | UTC+12 |
How the Time Zone Converter Works
The Time Zone Converter calculates the equivalent time in a target time zone by determining the UTC offset difference between the source and destination zones. Each time zone is defined as an offset from Coordinated Universal Time (UTC), formerly known as Greenwich Mean Time (GMT). The converter accounts for the current offset including any Daylight Saving Time (DST) adjustments that may be in effect.
Time Zone Conversion Formula
Target Time = Source Time + (Target UTC Offset - Source UTC Offset)
Example: 3:00 PM UTC to EST (UTC-5)
Target Time = 15:00 + (-5 - 0) = 10:00 AM EST
Understanding UTC and GMT
UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks and time. It is effectively the successor to GMT (Greenwich Mean Time) and is used as the reference point for all time zones. UTC does not observe daylight saving time, making it a stable reference for time conversions. Time zones are expressed as positive or negative offsets from UTC — for example, Eastern Standard Time (EST) is UTC-5, meaning it is 5 hours behind UTC.
Daylight Saving Time (DST)
Many time zones observe Daylight Saving Time, shifting clocks forward by one hour in spring and back in fall. This means the UTC offset for a given time zone can change throughout the year. For example, Eastern Time is UTC-5 during standard time (EST) but UTC-4 during daylight saving time (EDT). Not all regions observe DST — Arizona (US), most of Asia, Africa, and South America do not change their clocks. This converter uses the Intl API which automatically accounts for DST based on the date you select.
Solved Examples
Example 1: A meeting is scheduled at 3:00 PM EST. What time is it in London and Tokyo?
EST = UTC-5, London (GMT) = UTC+0, Tokyo (JST) = UTC+9
London: 3:00 PM + 5 hours = 8:00 PM GMT
Tokyo: 3:00 PM + 14 hours = 5:00 AM JST (next day)
Answer: 8:00 PM in London, 5:00 AM next day in Tokyo.
Example 2: A flight departs Sydney at 11:30 PM AEDT and takes 14 hours. What local time does it arrive in Los Angeles?
AEDT = UTC+11, PST = UTC-8. Difference = 19 hours behind.
Departure in LA time: 11:30 PM - 19h = 4:30 AM (same day)
Add flight time: 4:30 AM + 14h = 6:30 PM PST
Answer: Arrives at 6:30 PM Los Angeles time (same calendar day as departure).
Example 3: You need to call India (IST, UTC+5:30) when it is between 9 AM and 6 PM there. What hours work from New York (EST, UTC-5)?
IST is 10.5 hours ahead of EST
9 AM IST = 10:30 PM EST (previous night)
6 PM IST = 7:30 AM EST
Answer: Call between 10:30 PM and 7:30 AM EST (overnight window; only early morning EST works for daytime IST).
Practice Questions
1. A webinar starts at 10:00 AM PST (UTC-8). What time should participants in Berlin (CET, UTC+1) join?
Answer: 7:00 PM CET. Difference is +9 hours: 10:00 AM + 9 = 7:00 PM.
2. It is 2:00 AM Tuesday in Tokyo (UTC+9). What day and time is it in Chicago (CST, UTC-6)?
Answer: 11:00 AM Monday. Tokyo is 15 hours ahead: 2:00 AM - 15h = 11:00 AM previous day.
3. During US daylight saving time, EST becomes EDT (UTC-4). A 3 PM EDT call is what time in London (BST, UTC+1)?
Answer: 8:00 PM BST. EDT to BST difference is +5 hours: 3:00 PM + 5 = 8:00 PM.
Common Mistakes to Avoid
Confusing EST and EDT. Eastern Standard Time (UTC-5) and Eastern Daylight Time (UTC-4) differ by one hour. Check which is active for the date.
Forgetting the International Date Line. Converting from far-east Asia to the Americas can change the calendar date by one day.
Assuming all offsets are whole hours. India is UTC+5:30, Nepal is UTC+5:45, and parts of Australia use UTC+9:30.
Not checking DST transition dates. DST starts and ends on different dates in different countries. The US, EU, and Australia all switch on different weekends.
Key Takeaways
- Time zone conversion = Source Time + (Target UTC Offset - Source UTC Offset).
- UTC is the universal reference; all zones are expressed as offsets from it.
- DST changes the offset by 1 hour and occurs on different dates worldwide.
- Not all offsets are whole hours (India +5:30, Nepal +5:45, etc.).
- When scheduling internationally, always specify the timezone abbreviation or UTC offset.
- Crossing the date line changes the calendar day, not just the clock time.
Frequently Asked Questions
What is the difference between UTC and GMT?
UTC and GMT represent essentially the same time (zero offset), but UTC is the modern scientific standard based on atomic clocks, while GMT is the older astronomical standard based on solar time at the Royal Observatory in Greenwich, England. For practical purposes, they are interchangeable.
Does this converter handle Daylight Saving Time?
Yes. The converter uses the JavaScript Internationalization API which automatically applies DST rules based on the date and time zone you select. If a zone is currently observing DST, the offset will reflect that.
Why do some time zones have 30 or 45 minute offsets?
While most time zones are offset by whole hours from UTC, some regions use half-hour (UTC+5:30 for India) or 45-minute offsets (UTC+5:45 for Nepal). These were established based on geographic and political considerations.
How many time zones are there in the world?
There are 38 distinct time zones in use worldwide, ranging from UTC-12 to UTC+14. Some zones share the same offset but have different DST rules, resulting in over 400 named time zone identifiers in the IANA database.
What is the International Date Line?
The International Date Line (IDL) is an imaginary line running roughly along the 180th meridian in the Pacific Ocean. When you cross it going west, you advance one calendar day; going east, you go back one day. This is why converting between zones on opposite sides of the IDL can result in a different date.
How do I convert time for a conference call across multiple zones?
Enter the proposed meeting time in your local time zone as the source, then convert to each participant's time zone one at a time. Look for a time that falls within normal business hours (9 AM - 6 PM) for all participants.
Why does the converted time show "Next day" or "Previous day"?
When the time difference between zones is large enough, the converted time may fall on a different calendar day. For example, 11 PM in New York is 4 AM the next day in London (during EST). The day relation indicator helps you understand this date shift.