ISO 8601 Date Converter

Convert dates to and from ISO 8601 format — the international standard for date and time representation.

ISO 8601 Formats Reference

Date 2024-01-15 YYYY-MM-DD
Date & Time 2024-01-15T10:30:00 YYYY-MM-DDTHH:mm:ss
With UTC 2024-01-15T10:30:00Z Z = UTC timezone
With offset 2024-01-15T10:30:00+05:30 ±HH:MM offset
With ms 2024-01-15T10:30:00.000Z Milliseconds
Week date 2024-W03-1 Year-Week-Day
Ordinal 2024-015 Year-DayOfYear
Duration P1Y2M3DT4H5M6S Period: 1yr 2mo 3d 4h 5m 6s
Interval 2024-01-01/2024-12-31 Start/End

What is ISO 8601?

ISO 8601 is an international standard for representing dates and times. Published by the International Organization for Standardization (ISO), it defines an unambiguous, internationally agreed-upon format that eliminates confusion caused by regional date format variations. The most common ISO 8601 format is YYYY-MM-DDTHH:mm:ssZ (e.g., 2024-01-15T10:30:00Z).

ISO 8601 is the standard used by REST APIs (RFC 3339, a profile of ISO 8601), HTML input[type=datetime-local], JavaScript's Date.toISOString(), JSON serialization in most frameworks, database timestamps, and HTTP headers. It sorts lexicographically (alphabetically) in the same order as chronologically, making it ideal for storing dates as strings in databases and logs.

FAQ

What does the "T" and "Z" mean in ISO 8601?
The "T" is a separator between the date and time portions of the string (required by the standard to avoid ambiguity). The "Z" stands for "Zulu time" — the military term for UTC (Coordinated Universal Time). It indicates that the time is in UTC with no offset.
What is the difference between ISO 8601 and RFC 3339?
RFC 3339 is a subset of ISO 8601 specifically designed for use in internet protocols. It mandates some choices that ISO 8601 leaves optional (like requiring the T separator), and it is the format used in HTTP headers, JWT timestamps (iat, exp), and REST API date fields.