### Explanation of the LOOKUP function

There are 2 forms of the LOOKUP function:

- The 1st is calling for vectors (a
**lookup_vector**and a**result_vector**) - The 2nd is calling for an
**array**(which will automatically determine the orientation of your data set and where to look for the result)

**Explanation of the LOOKUP function (using VECTORS)**

There are 3 different arguments when using this form of the LOOKUP function:

- lookup_value
- lookup_vector
- result_vector

#### 1. lookup_value (boxed in blue)

This is the value you want to search for in your **lookup_vector**. You can either reference a cell (E3) like the example above or type your lookup value directly into the function. If you are searching for a string (text value), you need to put quotations before and after your **lookup_value**. If we did this in our example we would have to change E3 to “Forester” in the formula.

#### 2. lookup_vector (boxed in red)

This is the range of data you want to use to search for your **lookup_value**. In our example our **lookup_vector** is B3:B7 because this is the range of data in which we will be able to find our **lookup_value** “Forester”.

**Note:** Make sure your entire data set is sorted in ascending order (the sort criteria should be based on the data within your **lookup_vector**) or else the LOOKUP function will not work properly. In the example above, our data is sorted in ascending order.

#### 3. result_vector (boxed in purple)

This is range of data you want to return a result from. It must be the same size as your **lookup_vector**.

**In this example, the result returned by the LOOKUP function (using VECTORS) is $28,000.**

**Explanation of the LOOKUP function (using ARRAY)**

There are 2 different arguments when using this form of the LOOKUP function:

- lookup_value
- array

#### 1. lookup_value (boxed in blue)

This is the value you want to search for in your **lookup_vector**. You can either reference a cell (E3) like the example above or type your lookup value directly into the function. If you are searching for a string (text value), you need to put quotations before and after your **lookup_value**. If we did this in our example we would have to change E3 to “Forester” in the formula.

#### 1. array (boxed in red)

This is where the array form of the LOOKUP function becomes a bit tricky.

- It will automatically determine the orientation of your data and automatically search and return your result based on that.
- The function will always search for your
**lookup_value**within the “largest dimension” of your data set. - In our example, the vertical dimension of our
**array**is 5 and the horizontal dimension is 2. - Our
**array**is taller than it is wide. - This means the LOOKUP function will search for our
**lookup_value**in the 1st column of our**array**(searching down the rows).

**Note:** the example we are using is the 2nd scenario below (“More rows than columns”).

**How does LOOKUP (using ARRAY) figure out where to look for your lookup_value and how to find your result?**

- You have no control in terms of telling the function which row or column number to give you a result from (it will automatically bring the result from the last row or column depending on the orientation “dimensions” of your data)
- You cannot control which column or row the function searches for your
**lookup_value**(it will either choose the 1st row or 1st column depending on the orientation “dimensions” of your data)

**Note:** Your data still has to be sorted in ascending order or else your LOOKUP function will not work properly.

**In this example, the result returned by the LOOKUP function (using ARRAY) is $28,000.**

**IMPORTANT (MUST READ) – You need to understand how the LOOKUP function works**

**NOTE: In order to use the LOOKUP function properly, your data set has to be sorted in ascending order.**

In the example below we compare **LOOKUP (using vectors)** and **VLOOKUP** in 3 different scenarios.

**Reminder: Formula Syntax**

LOOKUP(lookup_value, lookup_vector, result_vector)

VLOOKUP(lookup_value, table_array, col_index_num, range_lookup)

### What are some differences between a LOOKUP and VLOOKUP function?

* (1) LOOKUP (using ARRAY) returns the result from the last column or row depending on the orientation of your data.

* (2) LOOKUP (using ARRAY) automatically determines the orientation of your data. Read the section in this article covering “Explanation of the LOOKUP function (using ARRAY)” to see what I mean.

### Some more examples of how a LOOKUP function (using ARRAY) works!

#### Go back to **Excel Tutorials**.