### Method 1 – Perform Interpolation of Linear 2D Data in Excel

#### 1.1 Apply Mathematical Equation for Linear Interpolation

There is an established mathematical equation for linear equations we will use.

`y= y1 + (x-x1)⨯(y2-y1)/(x2-x1)`

**STEPS:**

- Find out the coefficients of this equation.
- 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**.

- Use the following formula in the
**F12**cell:

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

- Press
**Enter**to observe the interpolated result.

#### 1.2 Interpolate Using a Trendline

**STEPS:**

- Insert a plot from the dataset.
- Click on the
**Insert**tab. - Click on the drop-down menu of the
**Insert Scatter (X, Y) or Bubble Chart**from the**Charts**group. - A wizard will open.
- From the wizard, select the
**Scatter**chart.

- The following chart is shown on the Excel Sheet.

- Click on the chart.
- You can see a plus (
**+**) icon. - Click on this icon and check Trendline.

- A trendline can be seen on the chart.
- Double-click on the trendline.
- The
**Format Trendline**window will appear on the right side of the Excel Sheet. - Check
**Display Equation on the chart.** - You can see a floating equation.

- Find the value of
**y**from this equation. - Use the following formula in the
**F6**cell:

`=93.631*F5+7.2024`

- Press
**Enter**to observe the interpolated result of sales.

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

There is an established mathematical equation for linear equations.

`y= mx+c`

**STEPS:**

- Use the following formula in the
**F6**cell:

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

- Press
**Enter**to observe the interpolated result.

**8**. So,

**x**=

**8**. “

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

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

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

**INTERCEPT**function calculates the interception.

#### 1.4 – Insert the FORECAST Function for Interpolation

**STEPS:**

- Use the following formula in the
**F6**cell:

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

- Press
**Enter**to observe the interpolated result.

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

**STEPS:**

- Use the following formula in the
**F6**cell:

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

- Press
**Enter**to observe the interpolated result.

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

**1**. The

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

### Method 2 – Perform Interpolation of Non-Linear 2D Data in Excel

#### 2.1 – Interpolation Using the GROWTH Function

**STEPS:**

- Use the following formula in the
**F6**cell:

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

- 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

**STEPS:**

- Use the following formula in the
**F6**cell:

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

**8**. We used the

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

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

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## Related Articles

- How to Calculate Logarithmic Interpolation in Excel
- 3D Interpolation in Excel
- How to Interpolate Time Series in Excel
- How to Perform Exponential Interpolation in Excel
- How to Do Polynomial Interpolation in Excel
- How to Apply Cubic Spline Interpolation in Excel

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