Time Zone Converter
Compare local times between cities with DST-aware calculations.
Understanding Time Zones & Daylight Saving Time
The world is divided into 24 primary time zones, each offset from Coordinated Universal Time (UTC) by whole or fractional hours. These zones generally follow lines of longitude, but political boundaries create many irregularities — China, for instance, uses a single time zone (UTC+8) despite spanning five geographical zones, while tiny Kiribati stretches across UTC+12 to UTC+14.
Daylight Saving Time (DST) adds another layer of complexity. Roughly 70 countries shift their clocks forward in spring and back in autumn, but the dates differ between the Northern and Southern hemispheres — and many equatorial nations don't observe DST at all. This means the time difference between two cities can change by one or even two hours throughout the year.
Our converter uses the IANA Time Zone Database (also known as the Olson database), the same authoritative source used by operating systems, programming languages, and airlines worldwide. By selecting a specific date, you see the exact offset in effect — including any DST adjustments — for both cities.
Tips for Scheduling Across Time Zones
Find Overlapping Business Hours
The 24-hour comparison chart above highlights business hours (9:00–17:00) for both cities. Aim for meetings during overlapping green blocks to ensure both parties are within normal working hours.
Account for DST Shifts
If you schedule a recurring weekly meeting, check the date selector around March and November. A meeting at 3 PM London / 10 AM New York could shift by an hour when one region changes clocks before the other.
Use Calendar Tools Wisely
Always send calendar invitations with the meeting time in a specific timezone (not just "3 PM"). Most calendar apps will automatically convert to each participant's local time, reducing confusion.