Question 1

What is an ISO 8601 duration?

Accepted Answer

An ISO 8601 duration is a standardized way to represent a period of time. It starts with 'P' (for period) followed by date components (Y, M, D) and optionally 'T' followed by time components (H, M, S). For example, P1Y2M3DT4H5M6S represents 1 year, 2 months, 3 days, 4 hours, 5 minutes, and 6 seconds.

Question 2

What do 'P' and 'T' mean in ISO 8601 durations?

Accepted Answer

'P' stands for 'period' and is required at the start of every ISO 8601 duration. 'T' is the time designator that separates the date portion (years, months, days) from the time portion (hours, minutes, seconds). For example, in PT1H30M, the 'T' indicates that 1H and 30M refer to hours and minutes, not months.

Question 3

Why is the total seconds approximate for months and years?

Accepted Answer

Because months and years have variable lengths (28–31 days for months, 365 or 366 for years), converting them to exact seconds is impossible without a specific start date. This tool uses standard approximations: 1 month = 30.44 days and 1 year = 365.25 days.

Question 4

Where are ISO 8601 durations used?

Accepted Answer

ISO 8601 durations are used in many systems: YouTube and Vimeo APIs return video lengths as durations, schema.org structured data uses them for recipe cook times and event durations, Java's Duration and Period classes parse them, PostgreSQL supports interval literals in this format, and many REST APIs use them for rate limits and timeouts.

ISO 8601 Duration Parser

ISO 8601 Duration String

Parsed Result

ISO 8601 Duration Format

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