How does a time zone converter work?

It uses the International Atomic Time (TAI) and UTC as base, applying fixed offsets and automatic DST rules for each time zone.

Coordinated Universal Time (UTC) is the primary time standard – time zones are expressed as offsets from UTC (e.g., UTC-5, UTC+9).

How is Daylight Saving Time handled?

Modern browsers automatically apply current DST rules based on the IANA time zone database.

Yes – add as many cities as you need and see live synchronized times.

Adjust the reference time – all other zones update instantly. Look for overlapping business hours.

Convert time across multiple time zones instantly. Add cities, adjust time in one zone – see live updates everywhere. Perfect for global meetings.

Reference Time & Date

Time zones are based on Coordinated Universal Time (UTC), the global standard:

All clocks worldwide reference UTC (no offset, no DST).
Each time zone has a fixed offset (e.g., New York is UTC-5, Tokyo is UTC+9).
Daylight Saving Time (DST): Some zones shift +1 hour in summer – rules are built into modern systems.
To convert: Take time in one zone → convert to UTC → apply target zone offset + DST.
Our tool uses your browser's built-in Internationalization API (Intl) for 100% accurate, up-to-date conversions.

Change the reference time in any zone – all others update instantly. No server calls, fully private.

Plan better with our other popular tools:

Word Counter Invoice Generator GPA Calculator

How does time zone conversion work?

Using UTC as base + zone offsets + automatic DST rules via browser API.

What is UTC?

The global time standard - all zones are offsets from UTC.

Is DST handled automatically?

Yes - up-to-date rules from the official IANA database.

Can I add unlimited zones?

Absolutely - add as many as you need.

How to schedule meetings?

Adjust reference time to find overlapping hours across zones.