In this article, we will show **how to do 2D interpolation in Excel**. It is possible to do the task of interpolation for both **linear **and **non-linear** datasets. You can easily interpolate in Excel if you properly follow the steps. The steps are quite simple. So, without any delay, let’s start the discussion.

## Download Practice Workbook

To practice by yourself, download the following workbook.

## 2 Suitable Ways to Do 2D Interpolation in Excel

We can easily do **2D interpolation** in Excel. There can be **2 **types of interpolation. We can interpolate for **linear data **and also for **non-linear data**. Here, we will show you **how to do 2D interpolation for both linear and non-linear methods**.

### 1. Perform Interpolation of Linear 2D Data in Excel

It is easy to perform **interpolation **of **linear 2D **data in Excel. We will show you **5** ways. Each method is quite easy. You can follow any process to do the task. To demonstrate the methods we will use the following dataset. In the dataset, there is information on the **weekly sales** of a **shop**. Here, sales records are for **odd **weeks. By interpolation, you can find sales of any **even **weeks. We will find an in-between sales value for week **8**. Let’s follow the steps below to learn these methods.

#### 1.1 Apply Mathematical Equation for Linear Interpolation

There is an established mathematical equation for linear equations.

`y= y1 + (x-x1)⨯(y2-y1)/(x2-x1)`

Using this mathematical equation, we can easily interpolate linear data. So, follow the steps below to learn the method.

**STEPS:**

- Firstly, find out the coefficients of this equation.
- So, place the values of
**x1**,**x2**,**y1**,**y2**and**x**in the**Excel Sheet**.

**8**. So,

**x**=

**8.**In the dataset, there is sales information for

**7**and

**9**. So,

**x1**=

**7**and

**x2**=

**9**. And

**y**represents the corresponding sales of these weeks. For this reason,

**y1**=

**670**and

**y2**=

**890**.

- Then, write down the following formula in the
**F12**cell:

`=F7+(F11-F5)*(F8-F7)/(F6-F5)`

- Then, press
**Enter**to observe the interpolated result.

#### 1.2 Interpolate Using Trendline in Excel

The **trendline **is one of the easiest methods for interpolating a linear equation. From the **trendline**, we can plot a linear line. And from this line, we can interpolate data.

**STEPS:**

- Firstly, we have to insert a plot from the dataset.
- To do so, click on the
**Insert**tab. - After that, click on the drop-down menu of the
**Insert Scatter (X, Y) or Bubble Chart**from the**Charts**group. - Instantly, a wizard will come out.
- From the wizard, select the
**Scatter**chart.

- As a result, the following chart is shown on the
**Excel Sheet.**

- In the following step, we will insert
**Trendline**. - To do so, click on the
**chart**. - Therefore, you can see a plus (
**+**) icon. - So, click on this icon and give a tick on the
**Trendline**.

- As a result, a trendline can be seen on the chart.
- Now,
**double-click**on the trendline. - Instantly, the
**Format Trendline**window will appear on the right side of the**Excel Sheet**. - Then, give a tick on
**Display Equation on chart.** - After that, look at the chart and you can see a
**floating equation**.

- So, you can find the value of
**y**from this equation. - Now, according to the
**equation**, write down the following formula in the**F6**cell:

`=93.631*F5+7.2024`

- Then, press
**Enter**to observe the interpolated result of sales.

#### 1.3 Interpolate 2D Data Using SLOPE and INTERCEPT Functions

We can also build up a formula using** the Slope function** and **the Intercept function**.

There is an established mathematical equation for linear equations.

`y= mx+c`

Using this equation, we will interpolate the **2D **data.

**STEPS:**

- Here, we need to find out the co-efficient of
**m**and**c**for interpolation. - Now, write down the following formula in the
**F6**cell:

`=SLOPE(C5:C12,B5:B12)*F5+INTERCEPT(C5:C12,B5:B12)`

- Then, press
**Enter**to observe the interpolated result.

**8**. So,

**x**=

**8**. “

**M**” denotes the slope of the straight line. And,

**c**represents the interception of the straight line with the vertical axis. With the

**SLOPE**function, we have calculated the slope. And, the

**INTERCEPT**function calculates the interception.

#### 1.4 Insert FORECAST Function for Interpolation

**Interpolation **is one kind of forecasting as we are predicting or anticipating the value. We don’t exactly know the real value exists. So, Excel’s in-built **the** **FORECAST Function** comes in quite handy in this regard.

**STEPS:**

- Now, write down the following formula in the
**F6**cell:

`=FORECAST(F5,C5:C12,B5:B12)`

- Then, press
**Enter**to observe the interpolated result.

#### 1.5 Interpolation of 2D Data Using TREND Function

Using **the Trend Function**, it is quite simple to interpolate from the linear data.

**STEPS:**

- Now, write down the following formula in the
**F6**cell:

`=TREND(C5:C12,B5:B12,F5,1)`

- Then, press
**Enter**to observe the interpolated result.

**TREND**function, we have set the constant

**1**. Here, the

**TREND**function predicts the linear trend of the dataset.

### 2. Do Interpolation of Non-Linear 2D Data in Excel

It is easy to **perform interpolation of non-linear 2D data in Excel**. We will show you **2** ways. Each method is quite easy. You just need to insert the formula. Here, you can follow any method to do the task. To demonstrate the methods we will use the following dataset. In the dataset, there is information on the **weekly sales** of a shop. Here, sales records are for odd weeks. By interpolation, you can find sales of any even weeks. We will find an in-between sales value for week **8**. Let’s follow the steps below to learn these methods.

#### 2.1 Interpolation in 2D Using GROWTH Function

Excel has another inbuilt function called **GROWTH**. **The GROWTH function** is more reliable and accurate for the exponential and non-linear datasets.

**STEPS:**

- Now, write down the following formula in the
**F6**cell:

`=GROWTH(C5:C12,B5:B12,F5,2)`

- Then, press
**Enter**to observe the interpolated result.

**GROWTH**function, we have set the constant

**2**.

#### 2.2 Combine FORECAST, INDEX, and MATCH Functions for Non-Linear Interpolation

Finding** non-linear **data is very difficult compared to** linear **data because it is difficult to find the pattern. The** FORECAST **function shows good results for interpolating linear datasets. But for the non-linear datasets, the result is not up to the mark. And the **GROWTH** function works well for the exponential dataset. For this reason, we have formulated a new formula combining the **FORECAST**, **INDEX **and **MATCH **functions.

**STEPS:**

- Now, write down the following formula in the
**F6**cell:

`=SLOPE(C5:C12,B5:B12)*F5+INTERCEPT(C5:C12,B5:B12)`

- Then, press
**Enter**to observe the interpolated result.

**MATCH**function to retrieve the positions of the value close to

**8**. Then, we have used the

**INDEX**function to determine the cell reference for that value. Then, we have created a dynamic range and the

**FORECAST**function predicts the interpolated value from this dynamic range.

## Conclusion

In this article, we have demonstrated how to do **2D interpolation in Excel. **There is a practice workbook at the beginning of the article. Go ahead and give it a try. To read similar articles, check out **the ExcelDemy website**. Last but not least, please use the comment section below to post any questions or make any suggestions you might have.