About

World Time Kit is a collection of time and date tools for people who work, travel or keep in touch across time zones: a world clock, a time zone converter, an international meeting planner, date calculators, sunrise and sunset times, and public-holiday calendars.

How the calculations work

Every conversion goes through UTC using the IANA time zone database that ships with your browser and our build system. We never store fixed offsets like “UTC-5” for a city, because offsets change with daylight saving time and legislation. Daylight saving edge cases — skipped hours in spring, repeated hours in autumn — are handled explicitly.

Principles

• Calculations happen in your browser; your inputs are not uploaded.
• Data we cannot verify is left out rather than guessed.
• Pages stay fast: static HTML with JavaScript only where a tool needs it.