Microsoft Excel

Microsoft Excel files (.xlsx, .xls) are widely used for storing tabular data with rich formatting.

What You Can Upload

• .xlsx files (Office Open XML, Excel 2007+)
• .xls files (BIFF8, Excel 97-2003)
• .xlsm files (macro-enabled workbooks: the data is read, the macros are ignored)
• .xlsb files (binary workbooks, BIFF12)
• ZIP archives with multiple Excel files

What You Get Out

DataMeans converts your data into multiple modern formats:

How to Export / Obtain Files

No special export needed - upload Excel files directly:

1. Locate your Excel file
2. Upload as-is or in a ZIP archive

Supported Features

• Multiple worksheets (each sheet becomes a table)
• Cell types: text, numbers, dates and times, yes/no
• Dates read through each cell's number format, in the 1900 and 1904 date systems, with the full value kept: a date shown in a time-only format keeps its date, and a duration shown as [h]:mm:ss keeps its hours past 24
• Formula values (calculated results, not formulas)
• Every cell a sheet holds, even when the workbook records a smaller range than it uses (common in reports exported from websites)
• Sheet names in any language
• A sheet with no cells (Excel's spare empty sheets, for one) is left out: the upload page notes it and offers no table for it
• The first row of each sheet read as the column names; a repeated name gets a suffix (Amount, Amount_1)

Known Limitations

• Formulas exported as their calculated values; formula text is never read
• A few rare formula types in legacy .xls files cannot be decoded. The upload page then says it cannot read the workbook. In Excel, copy each sheet and use Paste Special, Values to put it in a new workbook (or save each sheet as a CSV file), and upload that instead
• A cell showing a formula error (#N/A, #REF!, #DIV/0!) has no value, so it comes out empty, and the conversion report counts them
• Charts and pivot tables not extracted
• Macros and VBA code ignored
• Merged cells may cause alignment issues
• Rows with no values are left out and counted in the conversion report

Best Practices

• Use first row for column headers
• Avoid merged cells in data tables
• Keep one logical table per sheet
• Use consistent data types within columns

Note on the Excel formats. An .xlsx sheet holds at most 1,048,575 rows of data and 16,384 columns, and a legacy .xls sheet 65,535 rows and 256 columns. Rather than ship a file that looks complete but is silently cut short, DataMeans leaves a table out of any Excel format it does not fit and notes it in the job report. The .xlsx copy is also left out for tables of more than 8,000,000 cells (1,048,575 rows of 12 columns is 12.6 million), which take too long and too much memory to write, and the .xls copy for tables of more than 150,000 cells, which the legacy format takes far too long to write. The CSV, JSON and SQL outputs always contain every row.

Overview

Microsoft Excel uses proprietary binary and XML-based file formats for spreadsheet documents. The formats store tabular data, formulas, charts, and formatting in structured workbooks containing multiple worksheets. Excel files support complex data types, calculations, and rich formatting, making them suitable for data analysis and reporting.

History and Background

• 1982: Multiplan spreadsheet released for CP/M, later ported to MS-DOS.
• 1985: Microsoft Excel 1.0 released for the Macintosh, replacing Multiplan.
• 1987: Excel 2.0 for Windows, first Windows version.
• 1990: Excel 3.0 added toolbars, drawing tools, and 3D charts.
• 1992: Excel 4.0 introduced the AutoFill feature.
• 1993: Excel 5.0 introduced VBA, multi-sheet workbooks, and PivotTables.
• 1995: Excel 7.0 (Office 95), rewritten internally as a 32-bit application.
• 1997: Excel 8.0 (Office 97) introduced BIFF8 with Unicode strings and 65,536 rows.
• 1999: Excel 9.0 (Office 2000) added HTML document creation and publishing.
• 2002: Excel 10.0 (Office XP) introduced smart tags.
• 2003: Excel 11.0 (Office 2003) added XML import/export.
• 2006: Office Open XML formats standardized by Ecma International as ECMA-376 in December.
• 2007: Excel 12.0 introduced XLSX format, increased limits.
• 2008: OOXML approved as an ISO/IEC standard in April; ISO/IEC 29500:2008 published in November.
• 2010: Excel 14.0 added sparklines and slicers.
• 2013: Excel 15.0 introduced Flash Fill and Power Pivot data modeling.
• 2016: Excel 16.0 integrated Power Query (Get & Transform) and added forecasting functions.
• 2019: Excel 2019 added TEXTJOIN, IFS, and SWITCH functions plus map and funnel charts.
• 2021: Excel 2021 added XLOOKUP, XMATCH, LET, and dynamic array functions.
• 2024: Excel 2024 added charts that reference dynamic arrays, the IMAGE function, and 14 new text and array functions.

File Format Specifications

Binary Format (XLS/BIFF):

• Proprietary binary structure with BIFF (Binary Interchange File Format) records
• Stored in a Compound File Binary (OLE2) container; little-endian byte order
• Workbook stream named "Workbook" in BIFF8, "Book" in BIFF5/BIFF7; BIFF2-BIFF4 stored a single sheet as a raw record stream with no OLE2 container
• Each record begins with a 2-byte type identifier and a 2-byte size field; record data is capped at 8,224 bytes, with longer content split across Continue records
• File extension: .xls
• Maximum rows: 65,536; columns: 256 (Excel 97-2003)
• File size limit: 2 GB (Compound File Binary 512-byte-sector limit)

XML Format (XLSX/OOXML):

• ZIP archive containing XML files and resources
• Based on Office Open XML standard (ECMA-376, ISO/IEC 29500)
• Package layout follows the Open Packaging Conventions (OPC); every package must contain a [Content_Types].xml part mapping part names to content types
• The .xlsb variant keeps the same OPC/ZIP package but stores worksheet parts as binary records defined in the MS-XLSB specification
• File extension: .xlsx (workbook), .xlsm (macro-enabled), .xlsb (binary)
• Maximum rows: 1,048,576; columns: 16,384
• File size limit: Limited by available memory and system resources

Key Components:

• Workbook: Container for all sheets and metadata
• Worksheets: Individual spreadsheet tabs with data
• Shared Strings: Centralized text storage for efficiency
• Styles: Formatting definitions for cells
• Relationships: Links between components
• Drawings: Charts, shapes, images

Data Types and Structures

Workbook Structure:

• Worksheets organized as tabs
• Cells addressed by column letter + row number (A1, B2, etc.)
• Ranges defined by start:end notation (A1:B10)
• Named ranges and tables for organization
• Charts linked to worksheet data
• Pivot tables for data summarization

Version Differences

Compatibility Notes:

• .xlsx is the default file format in Excel 2007 and later
• .xls files can be opened in newer versions
• Opening an .xls file places the workbook in Compatibility Mode (shown in the title bar), keeping the 65,536-row, 256-column grid until the file is converted
• Some features lost when saving to older formats
• The Compatibility Checker runs automatically when saving a workbook to the Excel 97-2003 format and reports unsupported features
• Excel 2010 can open but not save Strict Open XML workbooks; Excel 2013 and later can read and write them
• VBA macros require .xlsm, .xlsb, or legacy .xls formats
• Workbooks may use the 1900 or 1904 date system; older Excel for Mac versions defaulted to 1904

Technical References

• Microsoft Excel Developer Documentation
• MS-XLS: Excel Binary File Format (.xls) Structure
• ECMA-376: Office Open XML File Formats
• Excel Specifications and Limits
• Wikipedia: Microsoft Excel