VLOOKUP, INDEX/MATCH, and Advanced Lookups with AI

Lookup formulas are the #1 thing people Google in spreadsheets. VLOOKUP alone has over 5 million searches per month. INDEX/MATCH confuses even experienced users. And cross-sheet lookups? Forget it — that’s where most people give up.

With AI, all of that complexity disappears. You just describe what you want to find.

🔄 Quick Recall: In the previous lesson, you learned to clean data by specifying exact formats and inconsistencies in your AI prompts. Lookup formulas follow the same principle: the more context you give AI about your sheet structure, the better the formula.

The Three Lookup Functions

Before asking AI for lookups, it helps to understand what each function does:

The good news: you don’t need to memorize any of this. Just tell AI what you need, and it picks the right function.

Simple Lookups: One Sheet

Scenario: You have a product list with names in column A and prices in column C. You want to find the price for a specific product.

AI prompt:

“In Google Sheets, I have product names in column A and prices in column C (rows 2 to 100). Create a formula that takes the product name in cell F2 and returns its price. Show ‘Not found’ if the product doesn’t exist.”

AI generates:

=IFERROR(VLOOKUP(F2, A2:C100, 3, FALSE), "Not found")

Notice how AI automatically adds IFERROR for the “Not found” case. It also correctly uses FALSE for exact match and 3 for the third column.

✅ Quick Check: In the VLOOKUP formula above, what does the number 3 represent? (Answer: The column index — return the value from the 3rd column of the range A2:C100, which is column C.)

Cross-Sheet Lookups

This is where most people struggle — and where AI shines brightest.

Scenario: You have an “Orders” sheet with product IDs and an “Inventory” sheet with product IDs, names, and stock levels. You want to pull stock levels into the Orders sheet.

AI prompt:

“I have two sheets. The ‘Orders’ sheet has order IDs in column A and product IDs in column B. The ‘Inventory’ sheet has product IDs in column A, product names in column B, and stock quantities in column C. Create a formula for column C of the Orders sheet that looks up each product ID in the Inventory sheet and returns the stock quantity. Show 0 if the product isn’t found.”

AI generates:

=IFERROR(VLOOKUP(B2, Inventory!A:C, 3, FALSE), 0)

The key detail: AI correctly references Inventory!A:C for the cross-sheet lookup because you named the sheets in your prompt.

Multi-Criteria Lookups

What if you need to match on TWO conditions? VLOOKUP can’t do this alone — but AI knows to use INDEX/MATCH.

Scenario: Find the sales amount where the salesperson is “Alice” AND the month is “January.”

AI prompt:

“Column A has salesperson names, column B has month names, and column C has sales amounts. Create a formula that returns the sales amount where column A is ‘Alice’ AND column B is ‘January’.”

AI generates (Excel):

=INDEX(C:C, MATCH(1, (A:A="Alice")*(B:B="January"), 0))

(Entered with Ctrl+Shift+Enter in older Excel versions, or auto-spills in newer versions.)

AI generates (Google Sheets):

=INDEX(C:C, MATCH(1, ARRAYFORMULA((A:A="Alice")*(B:B="January")), 0))

✅ Quick Check: Why can’t a standard VLOOKUP handle a two-criteria lookup? (Answer: VLOOKUP only matches on one column — the leftmost column of the range. For matching on two columns simultaneously, you need INDEX/MATCH with array logic.)

XLOOKUP: The Modern Alternative (Excel Only)

If you use Excel, XLOOKUP replaces both VLOOKUP and INDEX/MATCH with simpler syntax.

AI prompt:

“In Excel, product IDs are in column A and prices in column D. Use XLOOKUP to find the price for the product ID in cell G2. Return ‘N/A’ if not found.”

AI generates:

=XLOOKUP(G2, A:A, D:D, "N/A")

Much cleaner. No column index numbers, no TRUE/FALSE — just: what to find, where to look, what to return, and the fallback.

Note for Google Sheets users: XLOOKUP isn’t available in Google Sheets. But you can tell AI “I’m in Google Sheets” and it will automatically use VLOOKUP or INDEX/MATCH instead.

Debugging Lookup Errors

When a lookup formula returns #N/A or #REF!, paste the error into AI:

Prompt:

“This VLOOKUP returns #N/A: =VLOOKUP(B2, Products!A:C, 3, FALSE). Cell B2 contains ‘Widget-A’ and the Products sheet has ‘Widget-A’ in column A. What could cause this error?”

AI will suggest common causes: trailing spaces, different text encoding, hidden characters, or data type mismatches (number stored as text vs. actual number).

Practice Exercise

1. Create two sheets: “Employees” (Name, Department, Salary) and “Departments” (Department, Budget, Manager)
2. Ask AI for a formula that pulls each employee’s department budget into the Employees sheet
3. Ask AI for a formula that returns the manager name for each employee’s department
4. Try adding an error case: misspell one department name and see what happens

Key Takeaways

• Describe your lookup needs in plain English: what to find, where to look, what to return, and what happens on failure
• Always name your sheets in the prompt for cross-sheet lookups
• VLOOKUP works for simple lookups; INDEX/MATCH for multi-criteria or left-facing lookups
• XLOOKUP (Excel only) is the cleanest option when available
• Paste #N/A errors back into AI for instant debugging help

Up Next

In the next lesson, you’ll learn to create pivot tables with AI — summarizing thousands of rows into meaningful insights without memorizing any dialog boxes.