If you are looking for **how to take ****log of negative numbers ****in Excel**, then you are in the right place. The logarithmic function is a basic function in mathematics. Frequent mathematical formulas use logarithmic functions. In Excel, it is easy to take a log of positive numbers. But there is no specific formula for but taking the log of negative numbers. In this article, we’ll try to discuss how to take the log of negative numbers.

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## 3 Ways to Take Log of Negative Numbers in Excel

Excel offers some combinations of functions and some easy ways to find the log of negative numbers. To show this we have made a dataset named **Data for Computer Simulation of a Project** which has column headers as **Check Point Number** and **Distance from Sea Level (m)**. The dataset is like this.

Let’s see the ways to take the log of negative numbers.

### 1. Utilizing IF Function to Take Log of Negative Numbers

Initially, we’ll see what happens to negative numbers when we use a normal **LOG function**.

- Firstly, write the following formula in the
**D5**cell like this.

`=LOG(C5)`

Here, **C5 **is the **Distance from Sea Level(m)** of **Check Point 1**.

- Secondly, press
**ENTER**to find the output as**3979**.

- Thirdly, use
**Fill Handle**by holding the mouse to the**right-bottom**corner of the reference**D5**cell and sliding the cursor downwards like the picture below to find other outputs from cells**D6**to**D15**.

Immediately, we’ll get the output as shown in the following image.

More importantly, we can see that the outputs of the cells **D6, D9, D10, D12, **and **D15** are **#NUM!** Which means the output is invalid. This happens because the reference values of these output cells are negative, and the log of any negative number becomes a **complex number**. And **natural log function **makes **complex numbers** **invalid**.

Eventually, we can solve this issue by using an **IF function**. It is mainly a combination of **IF, ****COMPLEX****,** and** LOG **functions. This combined use of the functions gives an output of an **imaginary number** when we take a log of negative numbers.

To solve this issue, write the following formula in the **D5 **cell like this.

`=IF(C5<0,COMPLEX(LOG(ABS(C5)),PI()),LOG(C5))`

**Formula Breakdown**

**LOG(C5)**→ Returns**log**of**2.5****COMPLEX(LOG(ABS(C5))**→ Returns the absolute value if the**log(2.5)**is a complex number.**IF(C5<0,COMPLEX(LOG(ABS(C5)),PI()),LOG(C5))**→ Returns if the value of**C5**i.e. is less than**0**then**LOG(2.5)**is a complex number and**IF function**will return the absolute value of it. Otherwise, it will return normal positive value.

Secondly, press **ENTER** and use **Fill Handle** to find all the outputs like this.

Now, we can see that the log of negative numbers is no more **#NUM!**, rather they are shown as **imaginary numbers** as you can see **i**, the symbol of **imaginary numbers**, in the above output.

**Read More: ****Excel Formula If Cell Contains Negative Number (6 Examples)**

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**Count Negative Numbers in Excel (3 Easy Ways)****How to Add Negative Numbers in Excel (4 Easy Ways)****Excel Formula to Return Zero If Negative Value is Found****How to Show Negative Numbers in Excel (4 Quick Tricks)****Excel Negative Numbers in Brackets and Red (2 Examples)**

### 2. Using IMLOG10 Function to Take Log of Negative Numbers

We can also simply use the **IMLOG10 function** to find the log values of negative numbers. It gives the same output as the usage of the **IF **function.

- Firstly, write the following formula in the
**D5**cell like this.

`=IMLOG10(C5)`

Here, **10** refers to the **base** of the **LOG **function.

- Secondly, press
**ENTER**and use**Fill Handle**to find the other outputs like this.

**Read More: ****How to Put a Negative Number in Excel Formula (4 Easy Methods)**

### 3. Using Minimum Value to Find Comparative Log

We can also use the minimum value in a set of data to find a comparative log of negative numbers.

- Firstly, to find the minimum value among cells
**C5:C15**, select the cells and write the following formula in the**C17**

`=MIN(C5:C15)`

- Secondly, press
**ENTER**to get the output as**-7.6**.

Now, we need to take the positive value of that minimum value. Here it is **7.6**.

- Thirdly, in the
**C18**cell write the formula like this.

`=7.6+1`

Here, we want to take the value as **1** more than **7.6**. That’s why we have added **1**.

- Fourthly, press
**ENTER**to find the output as**6**.

- Fifthly, we need to place that
**6**in the**D**Column. - Sixthly, write the following formula in the
**E5**cell to get the sum of**C5**and**D5**

`=D5+C5`

- Seventhly, press
**ENTER**to find the output as**4**and use**Fill Handle**to get all the outputs in the**E6:E16**columns.

Eventually, we’ll see that all the values in the** E Column** are positive although the values are different from those in **C Column**. Basically, the base values are changed, and we’ll find the comparative log of the values.

- Eighthly, write the following formula in the
**F5**

`=LOG(E5)`

Here, **E5** is the sum of the cells** C5** and **D5**.

- Finally, press
**ENTER**and use**Fill Handle**to get all the outputs in the**F Column**like this.

**Read More: ****How to Change Positive Numbers to Negative in Excel (6 Ways)**

## Things to Remember

- If we want to avoid complex numbers as the output of a log of negative numbers, we need to use the comparative log. Because this comparative log method brings the output without complex numbers.
- We can use the
**LN**function instead of the**LOG**function by simply inserting**LN**in the places of**LOG**in the formulas of**Method 1**and**Method 2**to get the**ln**

## Conclusion

We can fin the log of any negative numbers if we study this article properly. Please feel free to visit our official Excel learning platform **ExcelDemy** for further queries.