The Classic Chore
Spreadsheets are where grunt work lives. A list typed by five different people, over five months, in five different styles.
Fixing it by hand means scrolling, copying, retyping, and hoping you didn’t miss a row. Claude can do the whole thing in one go:
What Claude Can Do With a Spreadsheet
Pretty much anything you’d do by hand, just faster and without getting bored:
| Chore | Example request |
|---|---|
| Clean up | “Remove empty rows and duplicates, and make all names start with a capital letter.” |
| Fix formats | “Make every date look like 2026-02-05, and turn ‘$200’ into plain numbers.” |
| Combine | “Merge the twelve monthly files in this folder into one sheet, with a Month column.” |
| Summarize | “Add a total for each client, and a grand total at the bottom.” |
| Chart | “Add a bar chart of total spending per month.” |
| Split | “Make one file per client, each with only their rows.” |
| Compare | “Which rows are in January’s file but missing from February’s?” |
The libraries doing the work are usually openpyxl (reads and edits Excel files, keeping your colors and formatting) and pandas (brilliant at sorting, grouping and adding things up). Claude will pick the right one if you ask it to research first.
Be Specific, Again
The 99% rule applies here too. Compare:
| Vague | Specific |
|---|---|
| “Clean up this spreadsheet.” | “Remove exact duplicate rows, delete fully empty rows, and trim spaces from the start and end of every name.” |
| “Fix the dates.” | “Dates are written many ways. Make them all look like 2026-02-05. If you’re not sure what a date means, list those rows for me instead of guessing.” |
That last sentence is a great habit: “if you’re not sure, ask me instead of guessing.” A date like 3/2/26 could mean March 2nd or February 3rd, and only you know which.
Check the Numbers
Spreadsheets hide mistakes well. A wrong total looks exactly like a right one. So after any change:
- Spot-check a few rows by hand against the original.
- Compare counts: “How many rows did the original have, and how many does the new one have? List the ones you removed.”
- Check one total yourself with a calculator.
Trust the speed. Verify the numbers.
Try it
Take a spreadsheet you actually use (or ask Claude to make a messy practice one). Copy it into a new folder, and ask Claude to clean it up and add totals, saving the result as a new file. Then check three rows and one total yourself.
See an example prompt
Make me a practice spreadsheet called practice.xlsx with 30 rows of messy made-up expenses: mixed date formats, some duplicates, some empty rows, amounts with and without "$". Then, in a separate step, clean it up and add a total per month. Save the clean version in an "output" folder, and tell me how many rows you removed and why.