In this tutorial, we will explain how to do interpolation in excel with **GROWTH **& **TREND **functions. In mathematics, interpolation is a statistical strategy for estimating an unknown value using related known variables. **Microsoft Excel** does not provide any direct function for interpolation. So, we use different functions to calculate a new value from known **X** and **Y** Values.

## Download Practice Workbook

We can download the practice workbook from here.

## 2 Methods to Do Interpolation with GROWTH & TREND Functions in Excel

In this tutorial, we’ll apply the **GROWTH **& **TREND **functions to interpolate a new value from a dataset. Apart from this, we’ll go over another method that uses a trendline to interpolate a new value.

### 1. Do Interpolation in Excel with GROWTH Function

First and foremost, we will interpolate a new value from the following dataset using **the GROWTH function**. The following dataset consists of values of different temperatures with corresponding densities. Using these data we want to estimate the density at a temperature of **35° celsius**.

Let’s see the steps to perform this action:

**STEPS:**

- To begin with, select cell
**F7**. - In addition, insert the following formula in that cell:

`=GROWTH(C5:C10,B5:B10,E7,1)`

- Then, press
**Enter**. - Lastly, in cell
**F7**we get the value of density for the temperature of**35°****celsius**. We can see that the value of the density in cell**F7**is**06 kg/m³**.

**Read More:** **How to Interpolate Between Two Values in Excel (6 Ways)**

### 2. Interpolation with TEND Function in Excel

In the second method, we will use **the TREND function** to do interpolation in excel. To illustrate this method we will use the same dataset that we used in the previous method. Also, we will interpolate data to get the value of density for **35°** **celsius**.

Just follow the below steps to execute this method.

**STEPS:**

- First, select cell
**F7**. - Next, type the following formula in that cell:

`=TREND(C5:C10,B5:B10,E7,1)`

- After that, hit
**Enter**. - Finally, we can see the value of density for
**35° celsius**temperature in cell**F7**. The estimated value of density is**11 kg/m³**.

**NOTE:**

If we notice we will see that the values that we get using the **GROWTH** function and **TREND** function are different. We get the value of density of **831.06 kg/m**³ when we use the **GROWTH** function and **831.11 kg/m³** when we use the **TREND **function. In terms of interpolation, the value that we get using the **GROWTH **function is more accurate than that we get using the **TREND **function.

**Read More:** **How to Interpolate in Excel Graph (6 Methods)**

## 3. Use Trendline in Excel to Do Nonlinear Interpolation

In this method, we will use neither the **GROWTH **function nor the **TREND **function to do interpolation in excel. Rather we will use a trendline to interpolate new values. While we are working with nonlinear data we need to figure out the function’s behavior first. With the help of a trend line, we will develop an equation that matches our data. Then, using that equation we will interpolate a new value.

To make you understand better we will again interpolate the value of density for **35° celsius** temperature.

Let’s take a look at the steps to perform this method.

**STEPS:**

- Firstly, select the data range (
**B5:C10**). - Secondly, go to the
**Insert**From the**Charts**section under the**Insert**tab and select the first scattered graph.

- So, we will get a graph like the following image.

- Thirdly, click on the graph.
- Then, go to
**Add Chart Element**>**Trendline**>**Linear**.

- The above action will return a trendline in the graph.
- Next, double-click on the trend line.

- Now, we can see a new sidebar named ‘
**Format Trendline**’. - Furthermore, scroll down and check the option ‘
**Display Equation on chart**’.

- The above action shows the equation on the graph that matches best with the pattern of our data.

- After that, insert the equation in cell
**F7**. Instead of**x**in the equation using the cell value of**E7**.

`=-0.562*E7 + 850.78`

- Press
**Enter**. - In the end, we get the value of density at
**35°**celsius temperature in cell**F7**.

**Read More:** **How to Do Linear Interpolation in Excel (7 Handy Methods)**

## Conclusion

In conclusion, this tutorial shows how to do interpolation in excel using the **GROWTH** and **TREND** functions. Use the practice worksheet that comes with this article to put your skills to the test. If you have any questions, please leave a comment below. Our team will make every effort to react to you as quickly as possible. Keep an eye out for more inventive **Microsoft Excel** solutions in the future.