How to use CSV Date Format Converter

Paste or choose a CSV and name the exact date-column header.
Select the explicit input and output formats and an invalid-date policy.
Run conversion and inspect converted, blank and invalid counts before downloading.

Example: CSV Date Format Converter

Change one date column without guessing its locale.

You add

CSV: name,date Alex,2026-10-03 Date column: date; separator: Comma; input: YYYY-MM-DD; output: DD/MM/YYYY; invalid rows: Refuse export.

You get

The date cell becomes 03/10/2026. The name cell remains Alex, and the output header remains name,date.

Options

CSV separator: Use the separator that actually divides the CSV cells; a selected file replaces the pasted CSV.
Input date format: This must match the actual stored date spelling. A mismatched choice can produce errors or interpret an ambiguous date differently.
Output date format: Select the output spelling required by the next application. This changes date text, not a spreadsheet cell’s formatting property.
Invalid date rows: Refuse stops the export when any date is invalid. Keep preserves that cell and provides a separate error report.

Supported inputs and limits

CSV up to 20 MiB, 100,000 data rows, 500 columns and 2,000,000 cells. Six explicit numeric date formats, Gregorian years 0001–9999. No locale guessing or time-zone conversion. Invalid dates are refused or retained with a report. CSV formula protection may prefix risky cell values.

Where your input is processed

This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

An ambiguous spelling needs an explicit format

03/04/2026 can mean different calendar dates under day-first and month-first conventions. The tool follows your selected format rather than guessing from the surrounding rows. Check a known date before converting a whole file, especially when it came from a different locale.

Keep-and-report does not repair invalid dates

An impossible date can either stop export or remain unchanged with an error report. Choosing Keep allows valid rows to convert while preserving invalid source text for review. Other cells remain text, although spreadsheet formula protection can prefix risky values. No time-zone or clock conversion is applied.

Questions about CSV Date Format Converter

Can the tool guess month-first dates?

No. Select the input format explicitly.

What happens to an impossible date?

Choose refusal or retain the original value with a report.

Are other columns changed?

Date conversion targets the named column. Export may add formula protection to risky values anywhere in the CSV.

Project manager: Tony Hines · Content updated 4 October 2026 · Report a problem