ISO 8601 Date Formatter
ISO 8601 is the international standard for date and time representation: YYYY-MM-DDTHH:mm:ss.sssZ. Format components: T separates date from time, Z indicates UTC (Zulu time), ±HH:mm for timezone offsets. Examples: 2026-02-05T14:30:00Z (UTC), 2026-02-05T09:30:00-05:00 (EST), 2026-02-05T15:30:00+01:00 (CET). Milliseconds (.sss) are optional. Used for API timestamps, database records, and cross-timezone communication. Unambiguous worldwide standard.
Convert dates and times to ISO 8601 format (YYYY-MM-DDTHH:mm:ss.sssZ). Supports UTC and timezone offsets, with or without milliseconds. Includes presets for common dates (now, today midnight, Unix epoch) and examples of different ISO 8601 formats. Perfect for API requests, database timestamps, and standardized date formatting.
Date & Time Input
Format Options
ISO 8601 Format Guide
YYYY-MM-DDTHH:mm:ss.sssZ- • 2026-02-05T14:30:00Z (UTC)
- • 2026-02-05T14:30:00.123Z (UTC with milliseconds)
- • 2026-02-05T09:30:00-05:00 (EST)
- • 2026-02-05T15:30:00+01:00 (CET)
- • T - Separator between date and time
- • Z - UTC timezone (Zulu time)
- • ±HH:mm - Timezone offset from UTC
- • .sss - Milliseconds (optional)
How to Use
- Enter your value in the input field
- Click the Calculate/Convert button
- Copy the result to your clipboard
Frequently Asked Questions
- What is ISO 8601 date format?
- ISO 8601 is the international standard for representing dates and times: YYYY-MM-DDTHH:mm:ss.sssZ. Example: 2026-02-05T14:30:00Z represents February 5, 2026 at 2:30 PM UTC. The format is unambiguous worldwide—no confusion between MM/DD and DD/MM. The "T" separates date from time, "Z" means UTC (zero offset), and milliseconds are optional.
- What is the difference between Z and timezone offsets?
- Z (Zulu time) means UTC with zero offset: 2026-02-05T14:30:00Z. Timezone offsets show hours and minutes from UTC: 2026-02-05T09:30:00-05:00 is EST (UTC-5), 2026-02-05T15:30:00+01:00 is CET (UTC+1). The times all refer to the same moment; only the representation differs. Use Z for storage and APIs; use offsets when displaying local time to users.
- Should I include milliseconds in ISO 8601 timestamps?
- Include milliseconds (.sss) when precision matters: financial transactions, event logging, high-frequency data. Omit milliseconds for human-readable timestamps, scheduled events, or date-only scenarios. Example with: 2026-02-05T14:30:00.123Z. Example without: 2026-02-05T14:30:00Z. Most APIs accept both formats.
- How do I convert ISO 8601 to Unix timestamp?
- Parse the ISO 8601 string to a Date object, then call .getTime() to get milliseconds since Unix epoch (1970-01-01). In JavaScript: new Date("2026-02-05T14:30:00Z").getTime() / 1000 gives Unix timestamp in seconds. Most programming languages have similar functions. ISO 8601 is more human-readable; Unix timestamp is simpler for calculations.
- What is RFC 3339 and how does it relate to ISO 8601?
- RFC 3339 is a profile of ISO 8601 commonly used in internet protocols and APIs. It requires the "T" separator, always uses 4-digit years, and mandates timezone information (Z or offset). While ISO 8601 permits several variations (like omitting separators: 20260205T143000Z), RFC 3339 enforces stricter rules for consistency. Most modern APIs follow RFC 3339 format.
- Can I use ISO 8601 for dates only (no time)?
- Yes, ISO 8601 supports date-only format: YYYY-MM-DD (e.g., 2026-02-05). This is useful for birthdays, deadlines, or events without specific times. You can also represent year-month (2026-02) or year only (2026). Time-only format exists too: HH:mm:ss. The full datetime format (with T separator) is most common for timestamps.