Time Zone Converter

The time zone converter helps you find the equivalent local time in any city or time zone around the world. It is designed for remote teams, travellers, and anyone scheduling international calls or flights who needs to compare times across regions instantly.

How to Use the Time Zone Converter

1. Enter the date and time you want to convert.
2. Select the source time zone, either by city name or UTC offset.
3. Select the target time zone you want to convert to.
4. Click Convert or read the instant result.
5. Add multiple time zones to compare several locations at once if the tool supports it.

The Formula

Time zone conversion works by calculating the offset of each time zone from Coordinated Universal Time (UTC), then computing the difference.

Converted time = Source time - Source UTC offset + Target UTC offset

For example, converting 3:00 PM London time (UTC+1 in summer) to New York time (UTC-4 in summer):

• 3:00 PM UTC+1 = 2:00 PM UTC
• 2:00 PM UTC - 4 hours = 10:00 AM UTC-4 (New York)

UTC is the global reference standard. Every time zone is defined as UTC plus or minus a number of hours (and sometimes half-hours or 45 minutes for some regions such as India and Nepal).

Real-World Example

You are in London (BST, UTC+1) and need to join a video call at 9:00 AM Pacific Time (PDT, UTC-7) on a weekday in June.

• 9:00 AM PDT = 9:00 AM + 7 hours = 4:00 PM UTC
• 4:00 PM UTC + 1 hour = 5:00 PM BST

You would join the call at 5:00 PM London time. This also means the call is outside normal working hours for you but within morning hours for your US colleague.

Daylight Saving Time and Why It Complicates Conversions

Daylight Saving Time (DST) shifts clocks forward by one hour in spring and back in autumn. The challenge is that different countries shift on different dates, and some countries (such as Japan, India, and most of Africa and Asia) do not observe DST at all. During the weeks when one country has shifted but another has not, the offset between them is temporarily different. The converter accounts for this automatically when you specify a date, but manually calculating conversions during DST transition weeks is error-prone.

Frequently Asked Questions

What is UTC and why is it used as the reference? UTC (Coordinated Universal Time) is the international time standard maintained by atomic clocks. It replaced GMT (Greenwich Mean Time) as the technical standard in 1972, though both refer to the same time in practice. UTC is used as a reference because it does not observe daylight saving time and remains constant year-round.

Why do some time zones have half-hour or 45-minute offsets? Most time zones use whole-hour offsets from UTC, but some regions adopted offsets based on local solar time or political decisions. India uses UTC+5:30, Nepal uses UTC+5:45, and Australia's Central Standard Time is UTC+9:30. These fractional offsets reflect historical and geographic factors.

How do I know if a country is currently observing DST? DST schedules change by country and sometimes by region within a country. The US and Canada shift on the second Sunday of March and the first Sunday of November. The UK shifts on the last Sunday of March and the last Sunday of October. The converter automatically applies the correct DST rule when you choose a location and date.

What does "Z" mean in timestamps like 2026-06-28T14:00:00Z? The "Z" stands for Zulu, which is NATO phonetic alphabet for Z, representing UTC (zero offset from UTC). A timestamp ending in Z means the time is expressed in UTC. This format is part of the ISO 8601 standard for date and time representation.

One Instant, Seven Clocks

Take a fixed instant, 2026-06-28T14:00:00Z, and read it in seven places.

Every row is the same moment. Only the label on the wall clock changes. The arithmetic is one addition or subtraction per location, performed against UTC rather than between pairs of cities, which is why going through UTC keeps the signs straight.

Worked Example: The Three Weeks the Gap Changes

A team in London and a team in New York hold a call at 09:00 New York time. For most of the year the gap between the cities is five hours. For three weeks in March it is four.

Thursday 5 March 2026. New York is on EST, UTC-5. London is on GMT, UTC+0. The gap is five hours, so the call starts at 14:00 in London.

Sunday 8 March 2026. Clocks in the United States move forward one hour. New York is now on EDT, UTC-4, while London is still on GMT. The gap is four hours, so the same 09:00 call now starts at 13:00 in London.

Sunday 29 March 2026. Clocks in the United Kingdom move forward. London is now on BST, UTC+1. The gap is back to five hours and the call returns to 14:00 London time.

Anyone who planned the month from a fixed five hour assumption loses an hour of their morning for three weeks. The window is short enough to be forgotten and long enough to matter.

Offset Reference Table

Notice that the southern hemisphere rows run the other way round. Adelaide is on standard time in June, which is why the first table shows ACST rather than the summer offset ACDT.

These are the rules in force for 2026. They are set by national law rather than by any technical standard, so a government can move them, and has done so at short notice in the past. That is the reason the tool takes its data from a published database instead of hard coding the numbers in the page.

Offset Rules

• Offsets and daylight saving rules come from the IANA time zone database, the reference list of zone names that operating systems and programming languages ship.
• Convert to UTC first, then to the target zone. Converting directly between two zones means looking up two offsets and performing two subtractions, and a sign slip doubles the error.
• Two places can share an offset without sharing an abbreviation. IST is used for India Standard Time, Irish Standard Time and Israel Standard Time, and the three are not the same offset.
• Abbreviations are neither unique nor stable. Use a zone name such as Europe/London or an offset such as UTC+01:00 in anything that has to survive a handover.
• The tool applies the rule that belongs to the date you enter, not the rule in force today. A date in 1995 can use a transition date that no longer applies.
• A conversion moves the label, not the moment. The instant is fixed, and only the wall clock reading changes.
• An offset is not a zone. A zone is a set of rules, and the offset is the value those rules produce on a given date.

Data Sources

Zone names, offsets and transition rules follow the IANA time zone database, maintained by the Internet Assigned Numbers Authority, a department of ICANN. The 2026 transition dates quoted above are the published rules for each region and can be changed by national legislation.

Finding the Overlap in a Working Day

Once the offsets are known, the overlap between two working days is arithmetic.

London and New York, five hours apart. London 09:00 to 17:00 is New York 04:00 to 12:00. New York 09:00 to 17:00 is London 14:00 to 22:00. The hours inside both working days are London 14:00 to 17:00, which is New York 09:00 to 12:00. That is three hours, and it is the whole of the usable window.

London and Los Angeles, eight hours apart in summer. London 09:00 to 17:00 is Los Angeles 01:00 to 09:00. Los Angeles 09:00 to 17:00 is London 17:00 to 01:00. No hour falls inside both working days. The nearest fit is the Los Angeles morning, 09:00 to 16:00, which is London 17:00 to midnight.

That is the practical cost of a wide offset. The call lands at the edge of somebody's day, and choosing a different hour only moves which side of the edge it falls on.

The same method extends to three cities. Write each working day as a range in UTC, then intersect the ranges. Two cities usually leave a comfortable window. Three rarely do. Four almost never, and when they do it is because one participant is working outside their normal hours.

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