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Issue 46 · 20 Oct 2026 · Easy · Free
Formula WhispererAI Excel and Google Sheets formula generator, free
You know exactly what you want the spreadsheet to do. You just don't know whether it's VLOOKUP, SUMIFS, or something with FILTER, and the formula you found online returns #N/A.
Say what you want a cell to do, in plain words. Get a working Excel or Google Sheets formula, explained piece by piece, plus the edge case that would break it.
- Category
- Automation
- Runs in
- ChatGPT
- Claude
- Gemini
- Copilot
What you put in and what you get out
Sample you can paste
Google Sheets. Sheet "Invoices", headers in row 1, data from row 2 down (about 400 rows, grows every week). A: invoice date B: client name C: amount (EUR) D: paid? (yes / no, sometimes blank) On another sheet, "Summary", I have client names in column A. In column B I want: the total amount still unpaid for that client, but only invoices from the last 30 days. Blank in D should count as unpaid.
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Formula Whisperer — You put in Google Sheets. Sheet "Invoices", headers in row 1, data from row 2 down. You get out Edge cases. Free from One Agent a Day.
When to use it
Use it when you know exactly what you want a cell to do but not whether it is VLOOKUP, SUMIFS, or FILTER.
When to skip it
It does not open your file. Describe your columns and a few example rows so the formula points at the right ranges.
30-second demo
0:00
The ask
Invoices sheet: date, client, amount, paid. Wants unpaid total per client, last 30 days only.
How it works
Most spreadsheet problems are the same handful of formulas: look something up, add up rows that match conditions, count things, pull a filtered list. The hard part is knowing which one, getting the syntax right for your app, and dealing with blanks, text-formatted dates, and names with a trailing space.
This agent takes a plain description of your sheet and what you want, and gives back one formula that fits your actual columns. It explains it piece by piece, so you can fix it yourself next time.
What to paste
Excel or Google Sheets (and the version if it's old Excel). Sheet names, what each column holds, where the data starts, and roughly how many rows. Then what you want the cell to do, in normal words. Mention blanks and anything messy.
What you get back
One formula, ready to paste, using your real sheet names and columns. A short breakdown of what each part does. Two or three test rows you can check by hand. Then the edge cases that would break it in your data, with a fix for each.
If there's a simpler approach than a formula, like a pivot table, it says so in one line. It won't hand you a 300-character LAMBDA when SUMIFS does the job.
Use it
Step 1
Describe your columns
Say which app (Excel or Google Sheets), the sheet names, which column holds what, and where the data starts. A few example values help a lot, especially dates and yes/no columns.
Step 2
Say what the cell should do
Plain words, including the awkward parts: blanks, text that looks like numbers, rows that will be added later. That is where copied formulas usually break.
Step 3
Run the prompt
New chat in ChatGPT, Claude, Gemini, or Copilot. Paste the prompt, then your description. If it asks a question, answer it. A wrong guess about your columns gives a formula that silently returns 0.
Step 4
Paste and spot-check
Put the formula in the first cell and drag it down. Check two rows by hand against the test cases it gave you. If you get an error, paste the error and the cell back in.
Prompt
formula-whisperer.prompt.txt
You write spreadsheet formulas for people who know what they want but not the syntax. You are practical: simplest formula that works, explained in plain words.
INPUT
- The app: Excel (which version if known) or Google Sheets.
- Sheet names, what each column contains, where headers and data start, rough row count, and sample values if given.
- What the formula should do, in plain words.
HOW TO WORK
1. Restate the task in one sentence using the user's columns. If a key detail is missing (which app, where the data is, how blanks should count), ask up to 3 short questions and stop.
2. Pick the simplest function that does the job. Prefer SUMIFS, COUNTIFS, XLOOKUP, INDEX/MATCH, FILTER, UNIQUE over nested IFs. Use only functions available in the user's app and version.
3. Write the formula with the user's real sheet names and columns. Use whole-column or bounded ranges that keep working as rows are added. Quote sheet names with spaces.
4. Check it against the data mentally: blanks, text stored as numbers or dates, trailing spaces, mixed case, duplicates, errors in source cells.
5. Write test cases a user can check by hand.
RULES
- One main formula. Give an alternative only if the user's app version may not support the first.
- Use the decimal and argument separators the user's locale suggests. If they used commas as decimals, use semicolons between arguments and say so.
- No VBA, Apps Script, or LAMBDA unless the user asks.
- If a pivot table or a built-in feature is clearly easier, say so in one line, then still give the formula.
OUTPUT
## Formula
Where to put it, then the formula in a code block. Say whether to drag it down or across.
## How it works
Each part of the formula on its own line with a short plain explanation.
## Check it
2 or 3 example rows with the result you should get.
## What could break it
Bullets: the problem, how you'd notice, and the fix.Copied it? Get tomorrow's prompt by email. Free, and you can leave whenever you want.
Questions about Formula Whisperer
Does it work for both Excel and Google Sheets?
Yes. Say which one you use. Where they differ, like FILTER or ARRAYFORMULA, it gives the right version.
Why does it list edge cases?
Formulas usually break on dates stored as text, trailing spaces, or blank rows. It names the ones that would break yours and how to fix them.
Is Formula Whisperer free?
Yes. The prompt is free to copy, download, and reuse under CC-BY-4.0. There is no sign-up on One Agent a Day. You only need access to a chat model such as ChatGPT, Claude and Gemini.
Which AI tools does Formula Whisperer work in?
It was written for ChatGPT, Claude, Gemini and Copilot. It is a plain-text prompt, so any capable chat model can run it. Paste the prompt first, then your input.
What do I paste into Formula Whisperer?
Describe your columns. Say which app (Excel or Google Sheets), the sheet names, which column holds what, and where the data starts. A few example values help a lot, especially dates and yes/no columns.
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