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Date Format Converter Online
Free online tool · No signup · Runs in your browser
Convert explicitly formatted dates in selected spreadsheet columns without guessing the day and month order.
Your data stays in this browser tool. No account or upload to a processing service required.
Instructions
- Paste a table with a header row, enter the date column numbers, and choose the exact input and output formats.
- Convert, review the preview, then download the CSV.
- Column numbers begin at 1.
Understanding your result
Converting 2024-02-29 to dd/mm/yyyy gives 29/02/2024. A value such as 03/04/2026 means different dates under the two slash formats, so choose the format your source actually uses. The converter follows that choice without guessing.
What to do if you have a problem
If a date is rejected, check zero padding and the calendar date itself. April 31 is invalid even when its characters match the format. If the cells contain timestamps or serial numbers, prepare those separately rather than choosing a format that only looks similar.
What to know before using the result
Accepts yyyy-mm-dd, dd/mm/yyyy and mm/dd/yyyy only, with zero-padded months and days. Rejects invalid calendar dates and checks leap years. Blank cells and headers are unchanged. No timestamps, Excel date serials or ambiguous date inference. Maximum 2 MB and 20,000 rows including the header.
These tools work with pasted text or supported CSV files rather than Excel workbook files. CSV exports contain values and do not preserve workbook formatting, formulas or multiple worksheets. Formula builders produce formula text to use in Excel. Data processing runs in the browser tool.
Try an example
Date,Event 2024-02-29,Launch 2026-10-02,Review
Summary
Save dates in the selected output format after confirming the source day and month order.