Looking for ways to do **polynomial interpolation **in Excel? Then, this is the right place for you. You can interpolate your data in different ways such as **linear**, polynomial, exponential etc. Here, you will find a step-by-step way to do **polynomial interpolation **in Excel.

**Table of Contents**hide

## Download Practice Workbook

You can download the workbook to practice yourself.

## What Is Interpolation?

**Interpolation **means predicting a value between two specific given data points using the dataset. **Data **can be **linear **or **nonlinear **and according to that the methods for interpolation also change.

## Step-by-Step Procedures to Do Polynomial Interpolation in Excel

Here, we have a dataset containing the value of **X **and **Y**, where** Y=F(X)**. Now, we will show you how you can **interpolate polynomially **the value of **Y **from the given value of **X** by drawing a **scatter chart** in Excel.

Follow the steps given below to do it on your own dataset.

### Step-01: Draw Scatter Chart

In the first step, you have to insert a scatter chart to do polynomial interpolation in Excel.

Here are the steps to do that.

**Steps:**

- Firstly, select cell range
**B5:C10**. - Then, go to the
**Insert**tab >> click on**Insert Scatter or Bubble Chart**>> select**Scatter**chart.

- Now, you will see that a
**Scatter Plot**has been inserted.

- After that, click on the
**“+”**sign to open**Chart Elements**. - Next, turn on the
**Axis Titles**option.

- Then, select the titles and type to change the
**Axis**and**Chart Titles**according to your wish.

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

### Step-02: Add Polynomial Trendline

Next, we will add **Trendline **in the **Scatter **plot to find the equation to interpolate data in Excel.

- To start with, click on the
**“+”**sign again to open**Chart Elements**. - After that, click on the sign beside the
**Trendline**option. - Then, click on
**More Options**.

- Now, the
**Format Trendline**toolbox will open. - Afterward, select the
**Polynomial**option and insert**Order**of the polynomial. - Next, turn on the
**Display Equation on chart**option.

- Thus, you can add a
**polynomial trendline**with the**equation**in your chart.

- After that, you can drag the position of the equation and make it more visible if you want.

**Read More: ****How to Apply Cubic Spline Interpolation in Excel (with Easy Steps)**

**Similar Readings**

**How to Interpolate Time Series in Excel (3 Easy Ways)****Interpolate in Excel Graph (6 Methods)****How to Do VLOOKUP and Interpolate in Excel (6 Ways)**

### Step-03: Find & Use Equation Found from Trendline

In the last steps, we will **use **the **equation **we found from the trendline to do **polynomial interpolation **of your data in Excel.

- Firstly, select
**Cell F5**and insert the following formula that we found from the**polynomial trendline**.

`=0.8696*F4^3-5.1174*F4^2+70.05*F4+8.4586`

- Then, press
**Enter**and drag right the**Fill Handle**tool to**AutoFill**the formula for the rest of the cells.

- Thus, you can do polynomial interpolation by drawing a scatter plot in Excel.

**Read More: ****How to Calculate Logarithmic Interpolation in Excel (2 Easy Ways)**

## How to Perform Exponential Interpolation in Excel

Additionally, here we will show you how to perform** exponential interpolation **using **the GROWTH function** in Excel. This function can predict the exponential growth of data.

The **GROWTH **function uses the following equation to interpolate data.

`y=b*e^x`

Here, **b **is the **y-intercept** of the curve.

Follow the steps given below to use this function to interpolate your data.

**Steps:**

- In the beginning, insert the following formula in
**Cell F5**and press**Enter**.

`=GROWTH($C$5:$C$10,$B$5:$B$10,F4,TRUE)`

- After that, drag right the
**Fill Handle**tool to**AutoFill**the formula for the rest of the cells.

- Thus, you can do
**exponential interpolation**in Excel.

**GROWTH**function, we inserted cell range

**C5:C10**as

**known_ys**, cell range

**B5:B10**as

**known_xs**,

**Cell F4**as

**new_xs**and

**TRUE**as

**const**.

**Read More: ****How to Do Interpolation with GROWTH & TREND Functions in Excel**

## Practice Section

In the article, you will find an Excel workbook like the image given below to practice on your own.

## Things to Remember

- In the beginning, you should check the pattern of your data before interpolating your data, if it is
**linear**or**nonlinear**. - You can use the
**FORECAST**&**TREND**functions if your data is**linear**. - However,
**polynomial Interpolation**is used to interpolate**nonlinear**data.

## Conclusion

So, in this article, we have shown you a step-by-step way to do **polynomial interpolation **in Excel. I hope you found this article interesting and helpful. If something seems difficult to understand, please leave a comment. Please let us know if there are any more alternatives that we may have missed. And visit **ExcelDemy** for many more articles like this. Thank you!