About

In global operations, temporal synchronization is a critical failure point. A miscalculation of a single hour due to Daylight Saving Time (DST) or Date Line crossovers can result in missed financial market openings, absent stakeholders in board meetings, or disrupted supply chain handovers. This tool is not merely a clock; it is a synchronization engine designed to align distributed teams.

Unlike standard converters that perform static arithmetic, this utility queries the browser's implementation of the IANA Time Zone Database for every calculation. This ensures that volatile variables - such as the specific minute a country transitions into DST or the unique 30 or 45 minute offsets found in regions like India, Nepal, and Newfoundland - are handled with algorithmic precision.

Formulas

The calculation of a target time t_target involves normalizing the base time t_base to a Universal Coordinated Time timestamp (TS_UTC) and then applying the target's zonal offset.

Let Offset(z, t) be a function that returns the offset in milliseconds for zone z at time t.

TS_UTC = t_base − Offset(z_base, t_base)

The target time is then derived:

t_target = TS_UTC + Offset(z_target, TS_UTC)

To determine the "Overlap Quality" Q for a meeting at hour h, we evaluate the local hour h_i for each participant i against the set of business hours B = [9, 17].

Reference Data

Region	Time Zone ID	Standard Offset	DST Rules
North America (East)	America/New_York	UTC−5	Starts Mar, Ends Nov
North America (Pacific)	America/Los_Angeles	UTC−8	Starts Mar, Ends Nov
Western Europe	Europe/London	UTC+0	Starts Mar, Ends Oct
Central Europe	Europe/Berlin	UTC+1	Starts Mar, Ends Oct
Eastern Europe	Europe/Moscow	UTC+3	FALSE (No DST)
South Asia	Asia/Kolkata	UTC+5:30	FALSE (No DST)
Japan	Asia/Tokyo	UTC+9	FALSE (No DST)
Australia (East)	Australia/Sydney	UTC+10	Starts Oct, Ends Apr
New Zealand	Pacific/Auckland	UTC+12	Starts Sep, Ends Apr
Middle East	Asia/Dubai	UTC+4	FALSE (No DST)
South America	America/Sao_Paulo	UTC−3	FALSE (Currently suspended)
China	Asia/Shanghai	UTC+8	FALSE (No DST)

Frequently Asked Questions

The logic does not assume integer-based time zones. It uses the `Intl` API to retrieve the exact minute offset. Consequently, converting 12:00 PM London to New Delhi will correctly result in 5:30 PM (UTC+5:30), and Adelaide will show its specific UTC+9:30 or UTC+10:30 time depending on the season.

This is the most dangerous period for scheduling errors, typically occurring in March and October/November. Because this tool queries the database for the *specific date* selected, it automatically detects this desynchronization. If you select a date in that "gap week," the tool will reflect the temporary offset (e.g., 4 hours instead of 5 between London and NY).

Standard Business Hours are defined as 09:00 to 17:00 (Green). Extended awake hours are 07:00-09:00 and 17:00-22:00 (Yellow). Sleep/Rest hours are 22:00 to 07:00 (Red). The "Find Best Overlap" algorithm prioritizes Green slots first, then Yellow.

Yes. You can select "Etc/UTC" or "Europe/London" (for GMT/BST). Note that UTC never changes, whereas GMT switches to BST (British Summer Time) in the summer. Always select the specific city (e.g., London) if you are coordinating with people, and "UTC" if you are coordinating with servers.