Time Zone Converter
Convert a local date and time between IANA time zones with DST-aware offsets.
Local browser tool
Choose a time and two locations
The source field is a wall-clock time in the source zone. Conversion uses the offset rules for that exact date, including daylight-saving changes.
Dates, selected zones, and results stay in this browser. Only the two zone preferences are saved locally.
Waiting for conversion
The same instant, shown in both places
Choose a source date, source timezone, and destination timezone to compare their local clocks and UTC offsets.
Working notes
Use Time Zone Converter with the boundary visible.
Time Zone Converter translates a local date and time between IANA time zones using the browser's date-specific offset and daylight-saving rules.
What is Time Zone Converter?
Time zones divide the world into regions that observe the same local time. There are over 400 entries in the IANA Time Zone Database, each encoding the complete history of UTC offsets and daylight saving time (DST) transitions for a region. Converting between time zones is more complex than adding or subtracting a fixed offset because DST rules change the offset on specific dates — and those dates differ by country. India (UTC+5:30) has no DST, while the US has four mainland zones with DST transitions in March and November. The EU observes DST but has discussed abolishing it. This tool uses the browser's built-in Intl API, which includes the complete IANA timezone database, to perform accurate conversions that account for historical and current DST rules. It detects and flags edge cases: times that do not exist (spring forward — clocks skip an hour) and times that occur twice (fall back — clocks repeat an hour). The converter shows the UTC instant and both local times with their UTC offsets, so you can verify the conversion is correct.
When to use it
- Scheduling meetings across time zones — convert a proposed meeting time between offices in different cities to find a time that works for everyone.
- Debugging timezone-related bugs — verify that a timestamp in your application converts correctly between the server timezone (usually UTC) and the user's local timezone.
- Planning deployments — convert a deployment window from your local time to the production server's timezone and the team's timezone.
- Setting monitoring alerts — configure alert schedules in UTC while verifying the local time in the region being monitored.
- Travel planning — convert flight departure and arrival times between departure city, connection city, and destination timezones.
How to use it
- 01Enter the wall-clock date and time in the source timezone.
- 02Select the source timezone from the IANA timezone list (e.g., America/New_York, Europe/London, Asia/Tokyo).
- 03Select the destination timezone.
- 04Review the converted time, UTC offsets for both zones, and the resolved UTC instant.
- 05If the source time falls in a DST gap (does not exist) or overlap (occurs twice), the tool flags the ambiguity.
Common mistakes
- Using fixed UTC offsets instead of timezone names — "UTC+5" does not account for DST changes. Always use IANA timezone names (Asia/Kolkata, America/New_York) for correct conversions.
- Ignoring DST transitions — a meeting at 2:30 AM on the day clocks spring forward does not exist in many US timezones. The converter detects and flags these gaps.
- Abbreviation ambiguity — "CST" could mean Central Standard Time (UTC-6), China Standard Time (UTC+8), or Cuba Standard Time (UTC-5). Use IANA names to avoid confusion.
- Converting far-future dates — timezone rules (including DST schedules) can change by legislation. Conversions for dates more than a year out may become inaccurate if rules change.
- Server time assumptions — "the server runs in UTC" may not be true. Verify the server's timezone before assuming timestamps are in UTC.
Synthetic example
Dhaka to London in summer
Input
2024-08-24 14:30 · Asia/Dhaka
Result
2024-08-24 09:30 · Europe/London (BST)
Related standards
Limits and data boundary
- Timezone rules can change after a browser release; confirm future operational schedules in the target system.
- Skipped daylight-saving times are rejected, while repeated times require an earlier or later occurrence.
Frequently asked questions
- Does this tool account for daylight saving time?
- Yes. Conversions use IANA timezone rules built into the browser, including DST transitions. The tool detects and flags skipped or repeated wall-clock times.
- What timezone database is used?
- The tool uses the IANA Time Zone Database (tzdata) bundled with your browser via the Intl API. Updates arrive with browser releases.
- Can I compare more than two timezones?
- The converter shows the source and destination zone. To compare additional zones, convert the same time using different destination timezones.
- Why does my conversion seem wrong by one hour?
- This usually means the date falls near a DST transition. Check whether DST is active in both the source and destination timezones on the specific date you entered.
Keep working