Starlight Tools

Time Zone Converter & Meeting Planner

Convert present, past, or future times between cities and compare as many locations as you need. Find overlapping working hours without signing up—this free, private, DST-aware tool runs in your browser.

Convert a city time

Enter the wall-clock time shown in the source location.

Destination locations

Converted time

Choose a valid source date, time, and destination.

24-hour comparison timeline

00:00 23:59

Drag or tap the slider. The red marker shows the selected instant in every row.

Working (09–17)Evening (17–22)Sleeping (22–09)

Flexible meeting planner

Set each participant’s preferred hours. The planner checks 15-minute starts, ranks full overlaps, and explains compromises.

Common time zone conversion examples

Select an example to load it into the converter. Each answer is calculated using the date-specific browser data.

How the conversion works

The source wall time is matched to the source location’s UTC offset for that specific date. That creates one UTC instant, which is then formatted using every destination’s offset at that same instant.

UTC = source time − source UTC offset
destination time = UTC + destination UTC offset

Worked example: on 15 July 2026, 09:00 in New York uses EDT (UTC−04:00), so the UTC instant is 13:00. London uses BST (UTC+01:00) at that instant, producing 14:00 in London.

Offsets must be date-specific because daylight-saving rules change through the year and can change politically. City-based zones such as America/New_York retain those rules; labels such as “EST” or “IST” can be fixed or ambiguous. Direct whole-hour arithmetic also fails for offsets such as India’s half hour and Nepal’s quarter hour.

Methodology, accuracy, and limitations

This converter uses Intl.DateTimeFormat and the time-zone data installed with your browser or operating system, which is derived from the IANA time zone database. It does not claim that your device contains the latest IANA release. IANA notes that its database is updated as governments change boundaries, offsets, and daylight-saving rules; see the IANA Time Zone Database and W3C guidance on working with time zones.

Date-dependent offsets. Each displayed abbreviation and offset is calculated at the selected instant, not assumed from today.
Skipped times. A spring-forward wall time with no matching instant is rejected with a warning; it is never silently moved.
Repeated times. If fall-back creates two matching instants, both are detected and you choose the earlier or later occurrence.
Limits. Abbreviations may be ambiguous, historical coverage varies by platform, and future law changes may make stored data stale.

Documented edge cases

  • United States: 02:30 on 8 March 2026 does not exist in New York; 01:30 on 1 November 2026 occurs twice.
  • Europe: 01:30 on 25 October 2026 occurs twice in London when BST returns to GMT.
  • Australia: Lord Howe Island uses a 30-minute seasonal clock change, not the usual hour.
  • Fractional offsets: Kolkata uses a half-hour offset; Kathmandu uses a quarter-hour offset.

Last reviewed: 15 July 2026.

Common time-zone mistakes

City zones versus abbreviations

“CST” and “IST” each have several meanings. Search for a representative city and confirm its country and UTC offset instead. IANA identifiers represent clocks that share a history of civil-time rules.

Daylight-saving changes

Spring transitions can skip wall times and autumn transitions can repeat them. This tool reports either state next to the source date-time field so the choice is visible.

Assuming the date stays the same

A valid conversion may land on the previous or next day. Check the weekday and rollover badge, particularly for Pacific crossings.

Time Zone Converter FAQs

How do I convert time between two cities?

Choose the source city, enter its local date and time, then add the destination city. The result converts that wall time to one UTC instant and displays the same instant in both cities.

Do future dates include daylight saving time?

Yes, when the browser’s installed time-zone data contains rules for that future date. Governments can change rules, so recheck far-future plans closer to the event.

Why can the destination have a different date?

Offsets can move the equivalent time across midnight or the International Date Line. The result marks previous-day and next-day changes explicitly.

What is the difference between UTC and GMT?

UTC is the modern international time standard. GMT is a time-zone name commonly used in the United Kingdom and is UTC+00:00 when observed; for ordinary clock conversion they often show the same time.

Why are abbreviations such as CST and IST ambiguous?

The same abbreviation can describe different regions. CST can mean North American Central Standard Time or China Standard Time, while IST can mean India, Irish, or Israel time. Choose a city-based IANA zone instead.

Should I choose EST or Eastern Time?

Choose a city such as America/New_York for Eastern Time because it changes between EST and EDT by date. A fixed EST offset does not represent daylight time.

Does the converter support half-hour and quarter-hour offsets?

Yes. Date-specific offsets support locations such as India at 30 minutes past the hour and Nepal or the Chatham Islands at 45 minutes past the hour.

Can I make historical conversions?

Yes, within the historical coverage and accuracy of the browser’s installed IANA-derived data. Very old civil-time records can be approximate or represented differently by platforms.

What if my city is not listed?

Search for a nearby city that follows the same civil-time rules or enter the IANA identifier. The full list depends on time zones supported by the browser.

How can I share a result?

Use Copy result for a readable message, Copy link for a restorable URL, or the calendar actions to download an ICS file or open Google or Outlook Calendar.

How do I find the best meeting time?

Set each participant’s working hours, the duration, date range, and weekend preference. The planner ranks full-overlap slots and, when none exist, identifies the least-disruptive alternatives and affected participants.

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