Standardize Dates in Excel & CSV Online
Fix mixed date formats in your spreadsheets. Normalize irregular dates into standard ISO YYYY-MM-DD or DD/MM/YYYY formats automatically.
Key Capabilities of Standardize Date Formats
ISO 8601 (YYYY-MM-DD) Standard
Converts dates into the universal YYYY-MM-DD format required by SQL, Google Sheets, and CRM databases.
Handles Excel Serial Numbers
Interprets Excel serial date numbers (e.g., 44986 -> 2023-03-01) exported by legacy ERP systems.
Multiple Separator Support
Recognizes dates written with slashes (/), hyphens (-), and dots (.) consistently.
Zero Overwrite of Non-Date Cells
Only valid date strings are formatted; regular text columns remain unchanged.
How to Standardize Date Formats in 3 Simple Steps
Upload Spreadsheet with Mixed Dates
Import files with dates written in various styles (e.g., 2023/04/12, 12-04-2023).
Automatic Date Normalization
Spreadsheet Fixer detects and standardizes dates across date columns into YYYY-MM-DD.
Download Uniform Dataset
Export clean spreadsheet ready for time-series analysis, chronological sorting, and charts.
Frequently Asked Questions
Which date format is recommended for databases?
The ISO 8601 standard format (YYYY-MM-DD) is universally recommended for SQL, CRM, Python pandas, and analytics tools.
Can it convert Excel serial date numbers?
Yes. It converts raw Excel numeric dates into human-readable date strings.