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ToolzKit

Time & Date

Time Zone Converter

Convert a date and time across multiple time zones at once, with UTC offsets and day differences.

Target time zones

Enter a source date/time to see conversions.

About the Time Zone Converter

Convert one source date and time into as many target time zones as you need, all at once. Each row shows the local date, time, UTC offset and whether the target falls on a different calendar day than the source, which is invaluable for scheduling meetings across regions.

How to use it

  1. 01Enter the source date and time, and select the source time zone.
  2. 02Add one or more target time zones using 'Add zone'.
  3. 03Read each target's local date, time, UTC offset, and day difference (+1/-1) versus the source.
  4. 04Remove or swap out target zones as needed.

Features

  • Converts a single moment in time into any number of target time zones simultaneously
  • Uses your browser's Intl.supportedValuesOf('timeZone') for a full IANA zone list where supported, falling back to a curated list of ~40 common zones
  • Shows UTC offset and a clear day-difference indicator for each target zone
  • Add or remove target zone rows freely

Practical examples

Scheduling a meeting

Set 9:00 AM in America/New_York as the source and add Europe/London and Asia/Tokyo to see local meeting times instantly.

Flight planning

Enter a departure time in one zone and check the equivalent time (and day) at the destination zone.

Remote team coordination

Keep a running list of target zones for teammates in different countries and check overlap at a glance.

Limitations

  • Historical time zone rules (before certain political changes) may not be reflected if your browser's ICU data doesn't include them.
  • Intl.supportedValuesOf is not available in every older browser; those browsers automatically fall back to the curated ~40-zone list.

Privacy

All time zone math is performed locally using the browser's built-in Intl.DateTimeFormat API. No date or location data leaves your device.

Read the full privacy policy for how the site as a whole handles data.

Frequently asked questions

Why does a target zone show +1d or -1d?

It means that, at the source moment you entered, the local calendar date in that target zone is one day ahead of or behind the source zone's date.

Does this account for daylight saving time?

Yes, the underlying Intl.DateTimeFormat API automatically applies daylight saving rules for the specific date you enter.

Can I add the same time zone twice?

Yes, there's no restriction, which can be useful for comparing labeled rows with different purposes.