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.

## 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.

## Polynomial Interpolation in Excel: Step-by-Step Procedures

Here, we have a dataset containing the values 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.

### 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.

### 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

## 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**.

## 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.

**Download Practice Workbook**

You can download the workbook to practice yourself.

## 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.

## Related Articles

- How to Do 2D Interpolation in Excel
- 3D Interpolation in Excel
- How to Interpolate Time Series in Excel
- How to Apply Cubic Spline Interpolation in Excel

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