TimeIs.today

IANA Time Zone Database

Zone names, current UTC offsets and the abbreviations people actually search for.

What is the IANA time zone database?

The IANA Time Zone Database — also called tzdata, zoneinfo or the Olson database — is the authoritative list of the world's time zones. It assigns each region a unique name in the form Area/Location, such as America/New_York, Europe/London or Asia/Kolkata. Every operating system, browser and programming language uses it to convert times correctly, because each entry encodes not just the current offset but the full history of daylight saving changes.

Abbreviations like EST or CST are convenient but ambiguous — CST can mean Central Standard Time in the US, China Standard Time or Cuba Standard Time. IANA names remove that ambiguity, which is why this site renders every city using its IANA zone.

Common time zones and their IANA names

Looking for a specific offset? Use the time zone list for a live clock per zone, the time zone converter to compare two zones, or the world clock to see many cities at once. Developers can also use the free time API.

Frequently asked questions

What is an IANA time zone?

A named region in the IANA Time Zone Database, like America/New_York, that stores the complete history of UTC offsets and daylight saving rules for that area.

Why use IANA names instead of abbreviations?

Abbreviations are ambiguous across countries, while IANA names are unique and carry DST rules — so software converts times reliably with them.

How many IANA time zones are there?

Around 600 zone names including aliases, which collapse to roughly 38 distinct UTC offsets at any given moment.