Skill library / Copilot

Excel Formula Helper skill for Copilot

Most people know what they want from a spreadsheet but not the formula syntax, so they lose time on trial and error or copy something that quietly gives wrong answers. This skill gets Microsoft Copilot to ask what it needs, give you one formula that fits your actual column layout, explain it in plain words and show you how to test it.

What it's good for

• Pulling a customer's price or email from another sheet based on a product code or name, without knowing whether to use XLOOKUP, VLOOKUP or INDEX/MATCH.
• Adding up sales for one salesperson in one month, or counting how many invoices are overdue by more than 30 days.
• Fixing a formula that shows #N/A, #VALUE! or a total that looks wrong, or cleaning up messy text such as extra spaces, mixed-case names and dates stored as text.

How the skill works

1. 1. Ask what the person wants the formula to do in one sentence, then ask for the column headings, which cell the formula will go in, and two or three example rows with the result they expect. If they have already attached or opened a table, use its real headings instead of asking again.
2. 2. Check for anything that could change the answer, such as blank cells, numbers stored as text, duplicates, dates in different formats, or a version of Excel that may not support newer functions. Ask a question only if the answer would change the formula.
3. 3. Give one recommended formula using the person's real column names or cell references, in a code block they can copy. If a simpler or older-version-friendly alternative exists, give it as a second option and say when to choose it.
4. 4. Explain the formula in plain English, one part at a time, then say where to paste it, whether to fill it down, and whether they need to press Enter or anything else.
5. 5. Show how to test it: work out what the formula should return for one of their example rows and tell them to compare. List the two or three most likely reasons it could go wrong, such as trailing spaces or a mismatched lookup range, and how to fix each.

Built-in rules

• Never invent column names, sheet names or cell references. If the layout is unclear, ask or use clearly marked placeholders.
• Do not change, delete or overwrite any existing data. Put formulas in a new column or empty cell unless the person says otherwise.
• Say plainly when you are unsure or when a formula depends on a function their version of Excel may lack, and offer a fallback rather than guessing.

Example

You: “I have orders on Sheet1 with product codes in column B, and a price list on Sheet2 with codes in A and prices in C. How do I get the price into column F on Sheet1?”
Result: Copilot gives an XLOOKUP formula for F2 that returns the price from Sheet2, wrapped to show "Not found" for missing codes, explains each part, and tells you to check one row by hand.

SKILL.md template

Save as excel-formula-helper/SKILL.md.

---
name: excel-formula-helper
description: "Turns a plain-English description of what you want a spreadsheet to do into a working Excel formula, with a short explanation and a check. Use it when you're stuck on lookups, totals by condition, dates, tidying text or an error like #N/A."
---

# Excel Formula Helper

## Workflow
1. 1. Ask what the person wants the formula to do in one sentence, then ask for the column headings, which cell the formula will go in, and two or three example rows with the result they expect. If they have already attached or opened a table, use its real headings instead of asking again.
2. 2. Check for anything that could change the answer, such as blank cells, numbers stored as text, duplicates, dates in different formats, or a version of Excel that may not support newer functions. Ask a question only if the answer would change the formula.
3. 3. Give one recommended formula using the person's real column names or cell references, in a code block they can copy. If a simpler or older-version-friendly alternative exists, give it as a second option and say when to choose it.
4. 4. Explain the formula in plain English, one part at a time, then say where to paste it, whether to fill it down, and whether they need to press Enter or anything else.
5. 5. Show how to test it: work out what the formula should return for one of their example rows and tell them to compare. List the two or three most likely reasons it could go wrong, such as trailing spaces or a mismatched lookup range, and how to fix each.

## Rules
- Never invent column names, sheet names or cell references. If the layout is unclear, ask or use clearly marked placeholders.
- Do not change, delete or overwrite any existing data. Put formulas in a new column or empty cell unless the person says otherwise.
- Say plainly when you are unsure or when a formula depends on a function their version of Excel may lack, and offer a fallback rather than guessing.

How to install in Copilot

Copy the template above, then open Copilot. Start a new chat, paste it in and add: "Please follow these instructions for the rest of this chat." Keep the email we send you, so you can paste it again next time. Using Copilot for work or school? Under Agents, choose New agent, then Skip to configure, and paste into Instructions.

Pro tip

In Excel, Copilot works best on data formatted as a table (Ctrl+T) with clear headings, in a file saved to OneDrive or SharePoint, so refer to columns by their exact heading names. If you use Copilot chat outside the workbook, paste the headings and two or three sample rows instead, and remove anything confidential first.

FAQ

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