A logarithm is a mathematical operation that determines how a particular number, referred to as the base, is increased with the aid of multiplying itself to attain some other number. There are plenty of examples of logarithm in our real life, like sound (decibel measures), earthquakes (Richter scale), the brightness of stars, and chemistry (pH measurement). In this article, we’ll show you 6 methods to calculate log in Excel.

**Table of Contents**Expand

## 1. Using **LOG** Function to Calculate Log in Excel

Before calculating the logarithm, you have to know what exactly a logarithm is. We are showing you a very easy and basic formula for a better understanding of this.

If, b^{a} = x, then Log_{b} x = a

For example,

5^{2} = 25 , so Log_{5} 25 = 2

Here, we’ve got a dataset for applying the **LOG function** on this and have the corresponding logarithm values.

**Steps: **

- First, click on cell
**D5**and type the following formula.

`=LOG(B5,C5)`

- Secondly, press
**ENTER**and as a result, you will get**2**as the logarithm value of**100.**

- Finally, use the
**Fill Handle**tool to copy the formula to the lower cells to get the results.

**Read More: Excel Logarithmic Scale Start at 0 **

## 2. Applying **LOG10** Function for Calculating Log in Excel

**LOG10 function** is mostly analogous to the **LOG **function. Just, here the base is set permanently as 10. So, we need not select the base manually.

**Steps:**

- At first, type the following formula in cell
**C5**.

`=LOG10(B5)`

- Now, press
**ENTER**to get the result and use the**Fill Handle**tool to achieve the logarithm values of other cells.

*Note**:**Here, we can see that in cells B5 & C5, the values are the same as in method 1. In method 1, for the first row, we used the base as 10 and got the logarithm value 2. Here we also get the same value. So, we could be sure about the fact that in the LOG10 function, the base is already defined as 10.*

**Read More:** **How to Calculate Antilog in Excel**

## 3. Inserting LN Function to Determine Log

**LN function** determines the **natural logarithm** value of a number. It takes the **base** as **e** which is a mathematical constant valued at approximately 2.71828.

**Steps:**

- First
**,**type the following formula in cell**C5**.

`=LN(B5)`

- Now, press
**ENTER**to the result and use the**Fill Handle**tool to obtain the other cell’s logarithm values.

**Read More: How to Calculate Natural Logarithm in Excel **

## 4. Exploring Function Library to Compute Log

Furthermore, we can do the above-mentioned 3 methods by exploring them in **Fu****nction Library**. For doing this, we must follow the steps below:

- Firstly, select cell
**D5**. Then, on the ribbon, click on**Formulas**>**Math & Trig**>**LN / LOG / LOG10**.(choose any function based on your demand).

- Let’s take the
**LOG**function from the drop-down menu for example. We can see a pop-up dialog box named**Function Arguments**. In the**Number**option, select cell**B5**and in the**Base**option, select cell**C5**. After filling up the arguments option, we can see our result in the pop-up dialog box. Now, click on**OK**.

- We can see our desired Logarithm value in cell
**D5**. Finally, using the**Fill Handle**tool, get the values of other cells.

## 5. Using Insert Function Option to Determine Log

An alternative way of doing the same task is to avail of the **Insert Function** option. The steps are as follows:

- First, select cell
**D5**and click on the**Insert Function**symbol. We can see a dialog box named**Insert Function**. Type**LOG**in the**Search**menu and select**Go**. Now, select the**LOG**function from the drop-down list and select**OK**.

- Now we have a similar dialog box named
**Function Arguments**like our previous method. Here input the**Number**and**Base**also in the blank options and click**OK**.

- Momentarily, we can see the logarithm value in cell
**D5**. Finally, use the**Fill Handle**tool and get the other values as well.

**Read More:** **How to Do Inverse Log in Excel **

## 6. Applying Excel VBA Code to Calculate Log

Also, we can use the Visual Basic for Applications (**VBA**) to create shortcodes to calculate logarithms in Excel. We’ll calculate the logarithm of 125 with the base value of 5. Follow the steps below:

- First, go to the sheet comprised of the data for the
**VBA**code and right-click on the**Sheet name**. Next, click on the**View Code**option.

- Secondly, right-click on
**Sheet7 (VBA Code)**from**Toggle Folders**. Then, select**Insert**>**Module.**

- Then, we will see a
**Code Module**box. Now, type down the below codes in that box and select**Run**.

```
Function LogAny(base As Double, number As Double) As Double
LogAny = Log(number) / Log(base)
End Function
Sub Log_Ex()
MsgBox LogAny(10, 100)
End Sub
```

- Eventually, you’ll see that your logarithm value is returned as 3 in a message box which is the same as the result of method 1 to method 5.

**Read More: How to Log Transform Data in Excel **

## Example of Calculating Log in Excel

Now we will show you a real-life application of logarithm using the **LOG **function in Excel.

We have a dataset of 6 solutions with their concentration in (μ mol/liter) unit. From this, we’ll find out the pH of the solutions and whether they are acidic or alkaline, or neutral.

So, the steps are as below:

- At first, select cell
**D5**and write down the formula as below, and press**ENTER**.

`=-(LOG(C5*POWER(10,-6),10))`

Here we are multiplying the value of concentration in cell **C5** by 10^{-6 }to get the unit in mol/liter from μ mol/liter.

- By pressing
**ENTER**, you can get the pH value of solution A in cell**D5.**Use the**Fill Handle**option and drag down to copy the formula in other cells and get the desired result.

- Afterward, click on cell
**E5**and type the formula as follows, and press**ENTER**.

`=IF(D5<7,"The solution is Acidic",IF(D5>7,"The solution is Alkaline","The solution is Neutral"))`

**Formula Breakdown:**

Here we’ve inserted a logic through the **IF function**. It’s like that- if our pH value is less than 7, then it will show “The solution is Acidic”; if our pH value is greater than 7, then it will show “The solution is Alkaline” and if the above 2 logic isn’t met, it will show “The solution is Neutral” in cell **E5**.

- This will show the statement “The solution is Acidic” because the pH value is less than 7. Now, use the
**Fill Handle**tool and drag it down to copy formulas in other cells to get the results.

**Read More:** **How to Calculate Logarithmic Growth in Excel**

## Common Errors While Calculating Log in Excel

Sometimes, the **LOG **function returns the value as an error. There are some common types of error and their reasons are given below to protect you from occurring error.

**1. #VALUE! Error**

It happens if the **number** or **base **argument is non-numeric.

**2. #NUM! Error**

This kind of error occurs when the **number** or **base** argument is zero or negative.

**3. #DIV/0! Error**

This error arises when the **base** argument is inserted as 1.

## Things to Remember

- The
**Number**argument in the**LOG**function cannot be zero or a negative number. It should always be a positive real number. - If the
**Base**argument is omitted, it is assumed to be 10 by the system.

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## Conclusion

In the article, we’ve tried to discuss the methods to calculate log in Excel. Hope you are satisfied enough by these methods, explanations, and examples. Please leave a comment if you have any queries.

## Related Articles

**How to Calculate Log Base 2 in Excel****How to Take Log of Negative Numbers in Excel****How to Plot Log Scale in Excel****How to Plot Log Log Graph in Excel**

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