Date Formatter
Standardise every date in a column to one format.
Mixed date formats are the most common reason a spreadsheet breaks downstream. Parse whatever your column contains — text, serials, DMY, MDY, ISO — and rewrite it all into one consistent, genuinely typed date format.
- Price
- Free
- Your files
- Never uploaded
- Runs
- In your browser
or drag it here
.xlsx, .xls, .csv · up to 50 MB · processed locally, never uploaded
Excel and spreadsheet files only. Export from Google Sheets as .xlsx or .csv.
Files stay on your device
What it does well
- Parses 30+ input patterns including month names and serial numbers
- Explicit DMY/MDY disambiguation so nothing is silently mis-parsed
- Writes real Excel date values, not text that merely looks like a date
How to use Date Formatter
- 1
Upload the file and pick the date column.
- 2
Confirm how ambiguous dates like 03/04/2025 should be read.
- 3
Choose the output format from the presets or write a custom pattern.
- 4
Apply and download.
Watch a walkthrough
Common problems and fixes
Dates still left-align after conversion.
Left alignment means they are still text. Enable “Write as date value” rather than the text-only formatting mode.
Some rows convert and others do not.
The unconverted rows use a different pattern. The report lists them with their raw value — add a second pass with the matching input pattern.
Frequently asked questions
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