24-Hour World Clock - Real-Time Global Time Converter
Track time across multiple time zones in 24-hour format. Features visual day/night indicators, UTC offsets, and printable reports. Accurate & DST-aware.
About
In an interconnected global economy, the 12-hour AM/PM system often leads to critical scheduling errors. The 24-Hour World Clock is designed for aviation, logistics, military, and distributed engineering teams who require unambiguous timekeeping. Unlike standard wall clocks, this tool visualizes the Day/Night Cycle for each location, reducing the risk of scheduling meetings during an off-shift.
This tool leverages the browser's native Intl.DateTimeFormat API to ensure nanosecond-precision adherence to local Daylight Saving Time (DST) rules without relying on potentially outdated server-side databases. It visualizes the offset relative to UTC, the primary time standard by which the world regulates clocks and time.
Formulas
The relationship between Local Time (Tlocal), Universal Time (TUTC), and the Zone Offset (Δt) is defined as:
Tlocal = TUTC + Δt
Where the offset Δt changes depending on Daylight Saving Time rules. For example, during summer in New York:
TEDT = TUTC − 4 hours
Reference Data
| Zone Name | Code | Offset (Standard) | Major Cities |
|---|---|---|---|
| Coordinated Universal Time | UTC/GMT | +00:00 | London (Winter), Reykjavik, Accra |
| Central European Time | CET | +01:00 | Paris, Berlin, Amsterdam, Rome |
| Eastern Standard Time | EST | -05:00 | New York, Washington D.C., Toronto |
| Pacific Standard Time | PST | -08:00 | Los Angeles, Vancouver, San Francisco |
| Japan Standard Time | JST | +09:00 | Tokyo, Osaka, Kyoto |
| Australian Eastern Time | AEST | +10:00 | Sydney, Melbourne, Canberra |
| India Standard Time | IST | +05:30 | New Delhi, Mumbai, Bangalore |
| China Standard Time | CST | +08:00 | Beijing, Shanghai, Hong Kong |