DD/MM/YYYY to ISO 8601 date (YYYY-MM-DD)
Databases, spreadsheets and file names work well with ISO dates because they sort in time order as plain text.
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How to use it
- Enter date dd/mm/yyyy.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
After the date is validated, write the 4-digit year, then month, then day, two digits each: YYYY-MM-DD.
Example
Inputs: Date DD/MM/YYYY = 05/03/2025. Result: ISO 8601: 2025-03-05; Weekday: Wednesday.
05/03/2025
2025-03-05
Limits and caveats
- Input is day-first only; for US dates use the MM/DD/YYYY tool.
- Years from 0001 to 9999, written with four digits.
Questions about this tool
What is the ISO 8601 date format?
Year, month, then day separated by hyphens, for example 2026-12-25.
Why do ISO dates sort correctly?
The largest unit comes first and each field has a fixed width, so text order matches time order.
What is the YYYYMMDD form?
It is the ISO 8601 basic format with no separators, common in file names.