Clean up an Excel file with AI: upload and instruct

What you need

• A computer
• A ChatGPT or Claude account (free plans can take file uploads, but limit daily use and file size)
• The Excel or CSV file to clean (check first for confidential or personal data)
• A spreadsheet program such as Excel (to check the result file)

What you get

A new spreadsheet fixed according to your rules, plus a summary of what changed and how many times. The original stays untouched. The example below uses fictional data.

Step by step

1. 1

   Write the cleanup rules in plain words first

   Write down the steps you do by hand today. Number them, with no more than 5, like "remove duplicates, fix dates, add a total". If you can explain what you do in words, the AI can do it too.

   You know it worked whenYou are ready when you have 3 to 5 numbered rules.

2. 2

   Copy the original and delete sensitive columns

   Make a copy of the original spreadsheet and call it a practice file. In the practice file, delete columns that have nothing to do with the cleanup, such as ID numbers, bank account numbers, and phone numbers, and save.

   You know it worked whenYou are ready when the practice file has no personal information columns left.

   TipFor work files, check your company's rules on uploading to an outside AI service first. If you are unsure, you can upload just a few rows.

3. 3

   Upload the file and send your request to ChatGPT or Claude

   Sign in at chatgpt.com or claude.ai. Click the paperclip (attach) button in the chat box and upload the practice spreadsheet. Swap your own rules into the prompt below, paste it, and send.

   Prompt to pasteCopy prompt

   Clean up the attached spreadsheet. Don't touch the original. Make a new file.
   
   Cleanup rules:
   1. If the same row appears more than once, keep only one
   2. Make every date cell use the same format, like 2026-10-31
   3. Trim spaces before and after the text in the Name column. Leave spaces inside a name, like "Mary Ann", as they are
   4. In the Amount column, remove "$" and commas and turn the values into numbers
   5. Add a total row for the Amount column at the bottom
   
   When you finish, tell me:
   - How many duplicate rows you removed
   - How many cells you reformatted
   - Any cells you left unchanged because they were unclear (row number and reason)
   
   Give me the result as a downloadable spreadsheet file.

   Make it yours

   • Change cleanup rules 1 to 5 to fit your file. Delete any rule you do not need.
   • Naming the columns makes it more accurate, for example: "Make the 'Payment date' column a date format".
   • If there are several sheets, give the range, such as "first sheet only".

   Want more control? (a slightly more technical version)

   Copy this version

   Write and run a Python script that cleans the attached spreadsheet.
   - Read it with pandas, remove duplicate rows, standardize date columns, convert the amount column to numbers
   - Save the result as an .xlsx with "_cleaned" added to the original file name
   - Print the number of changes to the console
   - Also give me the script as a file (clean.py) so I can run it weekly with the same rules

   You know it worked whenThe file name appears in the chat box, and after a moment the AI explains that it opened the file and shows the result.

   TipFile analysis may be limited on free plans. If it says it cannot read the file, save the spreadsheet as CSV and upload again.

4. 4

   Read the summary and check anything odd

   Read how many rows were removed, how many cells were changed, and the list of unclear cells it left alone. If a number is not what you expected, ask the AI where the difference is.

   You know it worked whenIf you see specific numbers like "removed 3 duplicate rows, fixed 12 date cells", it works.

5. 5

   Download the result spreadsheet

   The answer has a link or a file-name button such as "Download cleaned file". Click it to download and open it in your spreadsheet program. If there is no link, say "Give it to me again as a downloadable spreadsheet file."

   You know it worked whenIf the downloaded file opens in your spreadsheet program and has changed the way your rules said, it works.

   TipOpen it next to the original and compare a few rows by eye. For the total, check that your spreadsheet's SUM matches the value the AI gave.

6. 6

   Change it by asking

   If you do not like the result, ask for changes in the same chat. You do not need to upload the file again.

   TipTry things like "Move the total row to the top", "Use the format 10/31/2026 for dates", "Treat rows as duplicates only when both name and date match", or "Highlight only the problem rows in yellow and collect them on a separate sheet".

7. 7

   Try it on the real file

   When the practice result is right, upload the real file in the same chat (with the personal information columns removed) and say "Do this file with the same rules."

   You know it worked whenIf the second file comes back cleaned the same way, it works.

If you get stuck

Try next

• If you need the same cleanup every week, get a script (clean.py) with the advanced prompt. You just swap in one file and run it on your computer. Scheduling it to run automatically needs a tool like Claude Code or Codex, which is a step that needs a developer's help.
• Turning a cleaned spreadsheet into charts works the same way as in the "Spending dashboard" recipe.

Features used here

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