How to Use LOOKUP Function in Excel + Tips (Video in Khmer)

Hello everyone! Today I show you how to use LOOKUP function in Microsoft Excel step by step with simple example and video in Khmer.

You ever want search for a value in a list and get back the result from another column? That is what LOOKUP do! It look for your value in one column, then return the matching value from another column. Very useful for find data in big table fast!

1. What is LOOKUP Function in Excel?

LOOKUP function let you search for a value in one column or row, and return the matching value from another column or row.

Think of LOOKUP like find a student name in a list, then return their score. You give Excel the name, Excel go find it, then bring back the score for you. No need scroll up and down manually!

Two way to use LOOKUP:

Vector form — Search in one column, return from another column (most common use)
Array form — Search in first column or row of a range, return from last column or row

⚠️ Important: LOOKUP require your lookup column to be sorted A to Z (ascending order). If not sorted, result will be wrong! If your data not sorted, use VLOOKUP or XLOOKUP instead — they work with unsorted data.

2. Formula Syntax & Parameters

=LOOKUP(lookup_value, lookup_vector, [result_vector])

lookup_value — Required. The value you want to search for. Example: "John" or cell A2
lookup_vector — Required. The one-column or one-row range where Excel will search. Example: A2:A100
[result_vector] — Optional. The one-column or one-row range where Excel will get the result. Example: B2:B100. Must be same size as lookup_vector.

Note: If you skip result_vector, LOOKUP return the value from lookup_vector itself.

3. Practical Examples

Example 1: Find Student Score by Name

You have student name in column A (A2:A10) and their score in column B (B2:B10). You want find score for student name in cell D2:

=LOOKUP(D2, A2:A10, B2:B10)

👉 Result: Excel search for the name in D2 inside column A, then return the matching score from column B. Very fast!

💡 Tip: Make sure your name list in column A is sorted A to Z before use LOOKUP. If not sorted, LOOKUP may return wrong result!

Example 2: Find Product Price by Product Code

You have product code in column A (A2:A20) and price in column C (C2:C20). You want find price for product code "P005":

=LOOKUP("P005", A2:A20, C2:C20)

👉 Result: Excel find "P005" in column A and return the price from column C.

Example 3: Grade Score — Return Letter Grade

You have score in cell A2 and you want return letter grade (A, B, C, D, F). You can use LOOKUP with threshold list:

Set up your grade table:

E2:E6 = 0, 60, 70, 80, 90 (score threshold, must be sorted!)
F2:F6 = "F", "D", "C", "B", "A" (matching grade)

=LOOKUP(A2, E2:E6, F2:F6)

👉 Result: If score is 75, LOOKUP find it fall between 70 and 80, so return "C". Very useful for grade system!

💡 Tip: This threshold technique is very popular for grading, tax bracket, commission rate — any situation where value fall into a range. LOOKUP is perfect for this!

4. Video Tutorial in Khmer

Video 1 — LOOKUP Basic Example

Video 2 — LOOKUP Advanced Example

5. LOOKUP vs VLOOKUP vs XLOOKUP — What is Difference?

	LOOKUP	VLOOKUP	XLOOKUP
Need sorted data?	Yes ✅	No	No
Search direction	Left to right only	Left to right only	Any direction
Return multiple column?	No	No	Yes
Work on old Excel?	Yes	Yes	No (365/2021 only)
Easy to use?	Simple	Medium	Most flexible

Simple rule to remember:

Use LOOKUP when your data is sorted and you need simple lookup
Use VLOOKUP when data not sorted but you are on old Excel
Use XLOOKUP when you want most powerful and flexible lookup (Excel 365 or newer)

💡 Quick Tips for Using LOOKUP Function

Always sort your lookup column: LOOKUP need data sorted A to Z (ascending). If not sorted, result will be wrong — this is most common mistake!
Use for range/threshold lookup: LOOKUP is excellent when you want find which range a value fall into, like grade, tax bracket, or commission level.
Same size vector: Your lookup_vector and result_vector must have same number of row. If not same, you get error.
Consider upgrade to XLOOKUP: If you have Excel 365, XLOOKUP is better than LOOKUP — no need sort, can search any direction, more flexible.
Works on all Excel version: Unlike XLOOKUP, LOOKUP work on all Excel version including old Excel 2007, 2010, 2013.