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Date formatter

Convert an explicitly chosen date format across a CSV column. Validate calendar dates and keep invalid values visible in an exception report.

Fictional sample loaded for demonstration. Your file is not sent to a Rowlane server.

1. Bring in a table

CSV or TSV · UTF-8 text · up to 5 MiB, 20,000 records, and 100 columns

All values stay text, including IDs like 0017.
Quoted commas, quotes, and line breaks are preserved. Choose the delimiter if detection is wrong.
Choose the date field and its known formats

Loading table…

What this tool does

Choose the input convention before converting. Supported forms are exactly YYYY-MM-DD, DD/MM/YYYY, and MM/DD/YYYY. Day and month must use two digits. The calendar check handles month lengths and Gregorian leap-year rules without relying on the browser to guess a locale. Empty and invalid values stay unchanged and are listed for review.

How to use it

  1. Read the table and select the column containing calendar dates.
  2. Select an input format based on the source system, then choose an output format.
  3. Preview the result. Review unresolved values before using the exported table.

2. Check the input

Confirm the header and a few records before applying a rule.

Questions

What to expect

What happens to 29 February?

It is accepted only in a Gregorian leap year. For example, 2024-02-29 is valid and 2025-02-29 is not.

Will ambiguous dates be guessed?

No. You explicitly choose day-first or month-first. Verify the convention from your source before running.

Review the destination rules. A valid CSV or a clean report does not guarantee that another system will accept the file. Keep your original and verify any export before importing it.