## What Is LOG Function In Excel?

The

LOGfunction in Excel is an inbuiltMath & Trigfunction. It determines the logarithm of a given number to the specified base.Users can apply the

LOGExcel function in finance and statistics domains for tasks such as long-term perspective analysis of rate variations and regression analysis. And the function helps solve logarithmic equations in Excel.For example, the below table shows a set of numbers and corresponding base values, as per the given description statements, to determine the log of the specified numbers.

And suppose the requirement is to display the calculated log values in column D. Then, as per the **LOG Excel function meaning** explained above, we can apply the **LOG() **in the target cells and get the required data.

In the above **LOG Excel function example**, all the target cells’ formulas take two arguments, except in cell D4. The reason is that the default value of the **base** argument in the **LOG **Excel function is **10**. And so, we can ignore the argument in this case.

Further, as per the logic, raising the base to the power of the **LOG()** return value will result in the given number.

For example, the **LOG** function output in cell D2 is **2**. And if we raise the specified base value of **11** to power **2**, the result is **121**, which is the given number.

Thus, we can represent the above statements as:

**Log _{11}(121) = 2**

And it implies,

**11 ^{2} = 121**

##### Table of contents

###### Key Takeaways

- The
**LOG**Excel function calculates the logarithm of a number to the specified base. And the function output is the exponent, the value to which raising the base will result in the given number. - Users can use the
**LOG()**to solve logarithmic equations. And the function is useful in statistics and the financial domain for performing activities such as regression analysis and plotting graphs to represent rapidly changing prices. - The
**LOG**function accepts one mandatory argument,**number**, and an optional argument,**base**, as input. - We can use the
**LOG()**with other Excel functions, such as**POWER**and**IF**, to achieve fruitful results.

### LOG() Excel Formula

The **LOG **Excel function syntax is:

where,

**number**: The number we require to determine the logarithm for using the**LOG**Excel function.**base**: The logarithm’s base value.

While the first argument is mandatory, the second one is optional. And if we choose to ignore the second argument, the **LOG()** assumes the default **base **value, **10**.

Further, adhering to the below points will help us avoid the condition of the **LOG Excel function not working**.

- The
**number**argument value should be a positive real number. - If any of the supplied
**LOG Excel function arguments**are negative or zero, the**LOG**function will throw the**#NUM!**error. - If the provided
**base**value is**1**, the**LOG**function output will be the**#DIV/0!**error. - If any of the provided
**LOG Excel function arguments**are not numbers, the**LOG()**returns**#VALUE!**error.

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### How To Use LOG Excel Function?

The steps to use the **LOG **Excel Function are as follows:

- First, check whether the value we require the logarithm for is a positive real number. And ensure the specified
**base**value is not**0**,**1**, a negative number, or non-numeric. - Then, select the required target cell, and enter the
**LOG**Excel function. - Finally, press
**Enter**to view the logarithm of the given**number**.

The following example clearly explains the steps mentioned above to ensure we avoid facing the scenario of the **LOG Excel function not working**.

The table below contains a list of numbers and the corresponding base values.

And suppose the requirement is to compute the logarithm of each given number to the specified base and display the result in the respective column C cells. Then, applying the **LOG** function in the target cells will fetch us the required logarithm values.

**First, select the target cell C2, enter the LOG(), and then, press Enter.***=LOG(A2,B2)*

We can also directly supply the two number values as the**LOG()**arguments.

Alternatively, we can select the target cell and go to**Formulas**→**Math & Trig**→**LOG**to open the**Function Arguments**window and enter the**LOG()**arguments.

After we fill in the argument fields in the**Function Arguments**window, click**OK**, and the**LOG()**will get executed in the target cell.

Entering the numbers directly in the fields, instead of the cell references to numbers, will also give the same result.**Next, use the fill handle, and then, copy the formula in cell range C3:C6.**

Let us consider the cell C6 formula to see how the formula executes. The**LOG()**takes the values**0.64**and**4**as the**number**and**base**argument values. It then returns the logarithm of**0.64**to base**4**,**-0.3219281**. The result is negative because the given**number**is a decimal.

### Examples

Check out the below examples to understand the **LOG Excel function meaning **and apply the function effectively.

#### Example #1

We shall see how to use the **LOG **Excel function while performing logarithmic regression analysis.

Consider the first table contains a child’s age-wise weight data.

Suppose we need to conduct a logarithmic regression analysis with the given data. Then the steps are as follows:

First, we will create a scatter plot to get the logarithmic trendline and the regression formula for the above data.

**Step 1:**To begin with, select the cell range A1:B11, and then, click**Insert**→**Scatter (X, Y)**→**Scatter**to create a Scatter plot.

**Step 2:**Next, click the chart area to access the**Chart Elements**option and enable the**Axis Titles**and**Trendline**options.

**Step 3:**Then, update the chart title and axis titles by clicking the respective elements in the chart area.

**Step 4:**Next, right-click the horizontal axis and choose**Format Axis**in the contextual menu to open the**Format Axis**pane. And set the**Major**units as**1.0**.

Thus, now we can see every age value in the horizontal axis.

**Step 5:**Right-click the trendline and select**Format Trendline**in the contextual menu to open the**Format Trendline**pane.

**Step 6:**Next, select the**Logarithmic**trendline and the option to show the trendline equation.

And thus, the final chart will appear as depicted below:

Now, we shall use the **LOG **Excel function in the second table while performing the logarithmic regression analysis based on the equation obtained from the plot.

Suppose we need to predict the weight at the age of **7.5** years. Then, the steps are as follows:

**Step 7:**We shall fill in the parameter values in the second table.

As the age is **7.5 **years, **x** will take this value in cell L3.

As the trendline equation uses the **LN **excel function, which returns the natural logarithm of a given number, we can apply the **LOG()** and get the equivalent formula in cell L4.

*=LOG(L3,EXP(1))*

And we can get the **a** and **b **values from the trendline equation and enter them in cells L5:L6.

**Step 8:**Enter the values (determined in step 7) in the logarithmic regression formula to get the predicted weight at**7.5****years**in cell L8.

*=L6*L4+L5*

Thus, the predicted weight at the age of **7.5** years is **59.547 lb**. And we get the same value in the plot, as highlighted below.

Thus, we use the **LOG()** to determine the logarithm of the given **x **value in the logarithmic regression analysis.

#### Example #2

This **LOG Excel function example** shows how to use it with **POWER()**.

The below table contains two input value sets.

Suppose the requirement is to determine the logarithm of the number obtained by raising the given base to the exponent and display the results in cell range B5:B6 for the two input sets.

Then, we can use the **LOG() **and **POWER Excel function **in the target cells and get the required logarithm values.

**Step 1:**First, select the target cell B5, enter the below formula, and then, press**Enter**.

*=LOG(POWER(B2,B3))*

First, the **POWER() **raises the given base, **10**, to the power of **6**, thus returning the value **1000000**. Next, the **LOG() **considers **1000000** as the **number** argument. And as the **base** has the default value, **10**, the function omits it.

So, the **LOG() **returns the logarithm of **1000000** to the base **10** as **6**, the same as the given exponent value.

**Step 2:**Next, select the target cell B6, enter the below formula, and then press**Enter**.

*=LOG(POWER(C2,C3),C2)*

The **POWER() **raises the base **3** to the power of **4** to return the value **81**. Then, the **LOG()** accepts the **POWER()** output and the given base value as the two required arguments. And thus, it determines the logarithm of **81 **to the base **3** as **4**.

#### Example #3

Let us see how to apply the **LOG **Excel function to measure loudness in decibels (dB).

The equation to determine loudness is:

where,

**L(Ⅰ):**Loudness in dB**Ⅰ:**Sound intensity in W/m^{2}**Ⅰ**_{o}**:**The human hearing threshold

For example, the below table contains the values of the parameters mentioned above.

Suppose the requirement is to determine the loudness in dB, based on the given sound intensity, **I**, and display the result in cell B6. Then, we can apply the **LOG **Excel function in the target cell and get the required data.

**Step 1:**To begin with, select the target cell B6, enter the below formula, and then, press**Enter**.

*=10*LOG(B2/B3)*

In this example, the **LOG()** takes only one argument, **number**, and omits the second argument, **base**. The reason is that according to the mathematical expression, the base is **10**, the default value the **LOG()** takes.

So the **LOG() **returns the logarithm of the value **(400/10 ^{-12}) **to the base

**10**,

**14.60205999**. And finally, the formula multiplies the

**LOG()**output by 10 to give the output

**146.0205999 dB**as the loudness level.

### Important Things to Note

- Ensure the
**number**argument is a positive real number. - The
**LOG**Excel function considers**10**as the default value of the**base**argument if omitted. - For negative or zero as the
**LOG()**arguments, the function returns the**#NUM!**error. - For non-numeric arguments, the
**LOG**function output will be the**#VALUE!**error. - For a
**base**value of**1**, the**LOG**function throws the**#DIV/0!**error.

### Frequently Asked Questions (FAQs)

**1. How to apply the LOG function in Excel VBA?**

We can apply the **LOG** function in Excel VBA using the below method:**Application.WorksheetFunction.Log(number,base)**

The arguments in the above method have the same interpretation as the **LOG()** arguments explained in the **LOG()** **Excel Formula** section.

Let us see an example of how to use the above method in Excel VBA.

The below table contains a list of numbers and base values.

Suppose we need to determine the logarithm of the given numbers to the corresponding base values and display the output in column C. Then, here is how we can use the method mentioned above in Excel VBA to apply the **LOG** function in the target cells.**• Step 1: **With the active worksheet open, press **Alt** + **F11** to access the VBA Editor.**• Step 2: **Next, click the required **VBAProject **and then, select **Module** under the **Insert** tab to open a new module window, **Module1**.**• Step 3: **Then, enter the VBA code to apply the **LOG** function in the target cells.**Sub LOG_fn()**

Range(“C2”) = Application.WorksheetFunction.Log(Range(“A2”), Range(“B2”))

Range(“C3”) = Application.WorksheetFunction.Log(Range(“A3”), Range(“B3”))

Range(“C4”) = Application.WorksheetFunction.Log(Range(“A4”), Range(“B4”))

Range(“C5”) = Application.WorksheetFunction.Log(Range(“A5”), Range(“B5”))**End Sub****• Step 4: **Click the **Run Sub/UserForm** button to run the code.**• Step 5: **Open the active sheet to view the results in the target cells.

Let us consider the formula applied to cell C5. The method accepts the given number and base, **103** and **2.44**, as input. It then determines the logarithm of **103** to the base **2.44** as **5.195896**.

**2. What is the difference between the LOG, LN, and LOG10 functions?**

The difference between the **LOG**,** LN**, and **LOG10** functions is that the **LOG() **computes the logarithm of the given number to the specified base. On the other hand, the **LN()** and **LOG10() **determine a given number’s natural and base-10 logarithm, respectively.

**3. When can you use the LOG function in Excel?**

We can use the **LOG** function in Excel in the following scenarios:**• Business Analytics:** For performing regression analysis and creating charts to represent the data with a rapid rate of change graphically.**• Mathematical Applications:** To solve logarithmic equations.

### Download Template

This article must be helpful to understand the **LOG Excel Function**, with its formula and examples. You can download the template here to use it instantly.

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