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Use Claude Code with Excel in VS Code

You want a spreadsheet built - formulas, formatting, maybe a chart - but you don’t want to fight with Excel’s menus. Think of Claude Code as an assistant who knows Excel inside and out: you describe what you want in plain English, and it builds a real .xlsx file with working formulas. This tutorial shows you how to set up a project folder in VS Code and have Claude Code create and edit Excel spreadsheets for you.

Key Concepts

• xlsx skill - Built-in Claude Code capability for creating and editing .xlsx spreadsheets with real formulas, formatting, and charts
• Spreadsheet Viewer extension (formerly Excel Viewer) - VS Code extension that lets you preview and edit spreadsheet files without leaving the editor
• Formulas vs. hardcoded numbers - Claude Code writes actual Excel formulas (like =SUM(B2:B9)) so your sheet recalculates when you change the data

What You’ll Need

• Finished VS Code Basics
• Claude Code installed and working (see Install Claude Code on Windows or Install Claude Code on Mac)
• Microsoft Excel, LibreOffice Calc, or Google Sheets to open the finished file (optional - the Spreadsheet Viewer extension works without any of these)
• 15-20 minutes

Step 1: Install the Spreadsheet Viewer Extension in VS Code

• Open VS Code
• Click the Extensions icon in the left sidebar (or click View > Extensions)
• Search for GrapeCity.gc-excelviewer
• Click Install on Spreadsheet Viewer by MESCIUS

Note: This extension used to be called Excel Viewer by GrapeCity, and older guides and videos may still use that name. Searching for “Excel Viewer” now shows several other extensions, so search by the ID above to get the right one. The ID still starts with GrapeCity - that’s expected.

This lets you click any .xlsx file and see it rendered as a spreadsheet right inside VS Code, with no need to switch to another app.

Step 2: Create Your Project Folder

• Create a new folder on your computer (e.g., my-excel-project)
• In VS Code, click File > Open Folder and select your new folder
• Click Select Folder (Windows) or Open (Mac)

Step 3: Start Claude Code

• Click Terminal > New Terminal in VS Code
• Type this command and press Enter:

claude

• If this is your first time, a browser window opens for authentication - log in with your Claude account
• Return to VS Code once you see Claude’s welcome message in the terminal

Step 4: Create Your First Spreadsheet

• In the Claude Code terminal, type:

Create a spreadsheet called budget.xlsx with columns for Category, Monthly Amount, and Notes. Add 6 example expense categories like Rent, Groceries, and Utilities with realistic amounts. Add a Total row at the bottom that sums the Monthly Amount column using a formula.

• Press Enter
• Watch Claude write a Python script, run it, and produce budget.xlsx in your project folder
• Claude also recalculates the file so the formulas show real numbers, not blank cells

Step 5: Preview the Result

• In VS Code’s Explorer panel (left side), click budget.xlsx
• The Spreadsheet Viewer extension opens the file as a spreadsheet
• If you see scrambled text and symbols instead, VS Code opened the file as plain text - see Troubleshooting below
• Click the Total cell at the bottom - notice it’s a formula, not a typed-in number
• If you have Excel or LibreOffice Calc installed, you can also double-click the file in File Explorer (Windows) or Finder (Mac) to open it there instead

Step 6: Ask Claude to Add a Chart

• Back in the Claude Code terminal, type:

Add a pie chart to budget.xlsx showing each category's share of the total monthly spending.

• Press Enter
• Reopen budget.xlsx in the Spreadsheet Viewer tab (click the refresh icon, or close and reopen the file) to see the new chart

Step 7: Edit the Data and Ask Claude to Update It

• In the Spreadsheet Viewer, or in Excel/LibreOffice if you have it open, change one of the amounts (for example, double the Rent value)
• Save the file
• In the Claude Code terminal, type:

I changed some numbers in budget.xlsx. Recalculate the totals and make sure the chart still matches the data.

• Press Enter
• Claude reads your edits, recalculates the formulas, and confirms everything lines up

This is the core workflow: describe what you want, let Claude build it, check the result, and ask for changes in plain English.

Step 8: Ask Claude to Clean Up Messy Data

Claude Code is also useful for fixing spreadsheets that are already a mess.

• Type:

Create a messy_sales.csv file with 15 rows of sales data that has some issues: a few blank cells, inconsistent date formats, and one duplicate row. Then create a cleaned version called sales_clean.xlsx that fixes these problems and explain what you fixed.

• Press Enter
• Review the summary Claude gives you of what it found and fixed
• Open sales_clean.xlsx to confirm the data looks right

Next Steps

• Ask Claude to build a spreadsheet from a CSV file you already have (drag it into your project folder first)
• Try more advanced requests: “add conditional formatting so any category over $500 turns red”
• Ask Claude to add a second sheet that summarizes data from the first sheet
• Combine this with Use GitHub Desktop with Claude Code to save versions of your spreadsheets as you go
• Move on to Vibe Coding a Budget Tracker in Excel to build a full multi-sheet project

Troubleshooting

• budget.xlsx opens as scrambled text and symbols (starting with PK): VS Code is showing the raw file because no spreadsheet viewer handled it. The file itself is fine - an .xlsx is a compressed bundle, not plain text. Check that Spreadsheet Viewer by MESCIUS (GrapeCity.gc-excelviewer) is installed and enabled, then close the tab, right-click budget.xlsx in the Explorer panel, choose Open With…, and pick Excel Editor (Spreadsheet Viewer’s editor for .xlsx files). If another spreadsheet extension is also installed, choose Configure default editor for ‘*.xlsx’… in the same list and pick Excel Editor so single-clicking the file uses it from now on.
• Spreadsheet Viewer shows a blank or broken preview: Close the tab and reopen the file. If it still fails, open the file in Excel, LibreOffice Calc, or Google Sheets instead - the file itself is fine, it’s just a preview glitch.
• Formula cells show blank instead of a number: This usually means the file wasn’t recalculated after being written. Ask Claude: “Recalculate budget.xlsx and confirm there are no formula errors.”
• Claude’s changes don’t show up: Make sure you’re looking at the same file Claude edited (check the filename it mentions). Close and reopen the tab in VS Code to force a refresh.
• “claude is not recognized” in the terminal: Claude Code isn’t installed correctly. Revisit the installation guide for your platform.

Workflow Summary

• VS Code - Your project folder and a place to preview spreadsheets with the Spreadsheet Viewer extension
• Claude Code - Writes and edits real .xlsx files with working formulas, based on your plain-English requests
• Excel / LibreOffice / Google Sheets - Optional, for opening and manually tweaking the files Claude creates
• Iterate - Describe what you want, check the result, describe the next change

Created by Steven Ge on September 21, 2026.