Microsoft Excel Spreadsheet (MIME: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet) is the default file format for Microsoft Excel, the world's most popular spreadsheet application. It supports formulas, formatting, charts, pivot tables, macros, and multiple worksheets in a single file.
History and Development
XLSX was introduced with Microsoft Office 2007, replacing the older binary .xls format. It's based on Office Open XML (OOXML), standardized as ISO/IEC 29500. The format is essentially a ZIP archive containing XML files for worksheets, styles, and shared strings, making it more robust and recoverable than its predecessor.
Technical Specifications
- Format: ZIP archive containing XML files (Office Open XML)
- Max rows: 1,048,576 rows per sheet
- Max columns: 16,384 columns (A to XFD) per sheet
- Worksheets: Multiple sheets in a single workbook
- Features: Formulas, charts, pivot tables, conditional formatting, data validation
- Macros: Supported in .xlsm variant
- Max file size: ~4 GB (practical)
Common Use Cases
XLSX is used for financial modeling, business reporting, data analysis, project management, inventory tracking, budgeting, and any scenario requiring calculated or formatted tabular data. It's the standard format for sharing reports with business stakeholders.
XLSX vs Similar Formats
- XLSX vs CSV: XLSX supports formulas, formatting, and multiple sheets; CSV is plain text but universally compatible. Use XLSX for complex workbooks; CSV for data exchange.
- XLSX vs Google Sheets: Google Sheets is cloud-based with real-time collaboration; XLSX is offline-capable with more advanced features.
- XLSX vs XLS: XLSX is the modern XML-based format (smaller, more reliable); XLS is the legacy binary format (Office 97-2003).
How to Open and Edit
Microsoft Excel, Google Sheets, LibreOffice Calc, Apple Numbers, and WPS Office all open XLSX files. Python (openpyxl, pandas) and JavaScript (SheetJS) can read/write XLSX programmatically.
Frequently Asked Questions
What is the difference between XLS and XLSX?
XLS is the legacy binary format (Excel 97-2003) with a 65,536 row limit. XLSX is the modern XML-based format (Excel 2007+) supporting over 1 million rows, smaller file sizes, and better data recovery.
Can I open XLSX without Excel?
Yes! Google Sheets (free, web-based), LibreOffice Calc (free, desktop), and Apple Numbers can all open and edit XLSX files.
How large can an XLSX file be?
XLSX supports up to 1,048,576 rows × 16,384 columns per sheet. File size is limited to about 4 GB, though performance degrades significantly with files over 100 MB.