Last verified
XLSX Skill
VerifiedRead, write, and transform Excel spreadsheets from Claude Code without Excel installed
When it triggers
Use when reading or writing Excel workbook files
"Claude read twelve sheets, merged the data, and wrote a clean summary sheet. No VBA, no macros."
What is the XLSX Skill?
The XLSX Skill is an Anthropic-built Claude Code skill with full read-write access to Excel workbooks. It handles multi-sheet workbooks, preserves formulas, and writes updated files without requiring Excel, making spreadsheet automation a natural part of data and databases workflows in Claude Code sessions.
How does it work?
When Claude detects an Excel-related task, the skill loads a bundled spreadsheet library and opens the specified .xlsx or .xls file. Data is read into a structured in-memory representation that Claude can query, filter, and modify through natural language. After modification, the skill writes the result to a new file or overwrites the original, depending on your instruction.
For workflows spanning multiple document formats, the XLSX skill pairs with the PDF skill for report extraction and the DOCX skill for Word document handling, letting Claude move data between formats in one session.
When should you use it?
Use the XLSX skill when you need to automate Excel data transformation, generate reports from raw spreadsheet data, merge data from multiple workbooks, or populate template spreadsheets with dynamic data. It replaces manual Excel work and VBA macros for one-off and repeated data processing tasks.
Frequently asked questions
Does the XLSX skill preserve Excel formulas when writing files?
Yes. Formulas are preserved in the internal representation when you read a workbook. If you modify cells referenced by formulas, the skill recalculates dependent formulas before writing the output file, so the saved workbook is consistent.
Can the XLSX skill handle large workbooks with many rows?
The skill reads the entire workbook into memory, so very large files (500,000+ rows) can be slow. For large datasets, ask Claude to read only specific sheets or column ranges. Alternatively, convert to CSV first and use Claude's native file-reading capability, which is faster for pure data analysis.
Does the XLSX skill support .xls (legacy Excel) format as well as .xlsx?
Yes. The bundled library reads both .xls (Excel 97-2003) and .xlsx (Excel 2007+). Output files are always written in the modern .xlsx format, which is compatible with current Excel versions and Google Sheets.