About Timezone Converter

Timezone Converter displays the current time in multiple world timezones simultaneously and lets you convert any specific datetime across all of them at once. It sources its timezone list directly from the browser's built-in Intl API, ensuring that every IANA timezone — including regional ones like America/Indiana/Indianapolis — is available, with Daylight Saving Time offsets automatically applied for the selected date.

A built-in Meeting Planner heatmap visualizes which hours fall within 9-to-5 working hours across all your selected timezones simultaneously, making it easy to identify overlap windows for distributed team scheduling. The live clock mode updates every second. No data leaves your browser.

Common Use Cases

Scheduling a cross-team meeting with participants in New York, London, Bangalore, and Tokyo by finding a time slot that falls within business hours for the most attendees.
Verifying what local time a UTC deployment window, incident alert, or scheduled cron job corresponds to for on-call engineers in different regions.
Quickly checking whether a colleague in a specific city is currently in their working hours before sending an urgent message.
Preparing a travel itinerary by converting flight departure and arrival times from local time to UTC and back to the destination timezone.

How to Use

The tool starts with your local timezone pre-loaded alongside a selection of major cities. The live clock checkbox keeps all cards ticking in real time.
To compare a specific time, uncheck "Live clock" and use the datetime picker to enter the date and time you want to convert.
Add more timezones using the "Add timezone" dropdown — search by continent group and city name. Remove any card with the X button that appears on hover.
Scroll down to the Meeting Planner to see a heatmap of working hours across all selected zones; green cells are 9 AM–6 PM local time.

Frequently Asked Questions

How does the tool handle Daylight Saving Time?

The tool uses the browser's Intl.DateTimeFormat API with IANA timezone identifiers (e.g., America/New_York). This API automatically applies the correct UTC offset for the selected date, including DST transitions. So if you pick a date in December the tool shows EST (UTC-5), and a date in July shows EDT (UTC-4) — without any manual adjustment needed.

What is the difference between a timezone abbreviation and an IANA timezone?

Abbreviations like EST, IST, or CST are ambiguous — IST alone refers to India Standard Time, Irish Standard Time, and Israel Standard Time. IANA timezone identifiers like Asia/Kolkata or Europe/Dublin are unambiguous and encode both the geographic location and the historical rules for offset changes. This tool always uses IANA identifiers internally so conversions are unambiguous, while showing the short abbreviation for readability.

Can I bookmark a specific set of timezones?

Currently the tool resets to a default set of timezones on each visit, but you can click "Reset" at any time to restore the defaults. Your browser tab remains open with your custom selection as long as you keep the page open. A future version may support saving selections to localStorage for persistence across sessions.