Data interpolation is a very important thing when we analyze an experiment or we want to predict or determine the results of an event. For instance, if we have data on two different occasions, we can determine the data between those occasions by interpolation. This article will briefly describe **6** methods on how to **interpolate **between two values in Excel. In the dataset, we have some **X Coordinates **and **Y Coordinates**.

**Table of Contents**hide

## Download Practice Workbook

## 6 Ways to Interpolate Between Two Values in Excel

**1. Applying FORECAST/FORECAST.LINEAR Function to Interpolate Between Two Values in Excel**

The simplest way to **interpolate** between two values is to use the **FORECAST/FORECAST.LINEAR **function. Let’s go through the description below.

**Steps:**

- Determine which value you want to
**interpolate**and make new**rows**for the value you want to**interpolate**and the**interpolated**In this case I want to**interpolate**between**8**and**9**so I chose a value of**8.5**.

- Now type the following formula in cell
**B15**.

`=FORECAST(C14,C5:C12,B5:B12)`

Here, the **FORECAST **function determines the **interpolated **value in cell **C15 **via **linear regression**. It works on the **ranges B5:B12 **(as **known_Xs**) and **C5:C12 **(as **known_Ys**).

- Hit the
**ENTER**button and you will see the**interpolated**value in cell**C15**.

- You can also use the
**LINEAR**function in this case. Just put**FORECAST.LINEAR**instead of**FORECAST**in the formula.

`=FORECAST.LINEAR(C14,C5:C12,B5:B12)`

- Hit
**ENTER**and you will see the same**interpolated**value as before.

Thus you can easily **interpolate **between two values using the **FORECAST **function.

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

**2. Using the Combination of Excel XLOOKUP and FORECAST Functions to Interpolate Between Two Values**

If you want to **interpolate **within a small **range **of the dataset, you can use the **XLOOKUP **function to extract the **coordinates** in the **range **and **interpolate **a value within them. Suppose we want to **interpolate **the value **6** in **B9:C10**. Let’s discuss the procedure below.

**Steps:**

- First, make some modifications to the dataset to place the
**coordinates**.

- Type the following formula in cell
**F7**.

`=XLOOKUP(C14, B5:B12,B5:B12,,-1,1)`

The **XLOOKUP **function looks up the value in **C14**, searches for this value in the **range B5:B12, **and returns the value which is adjacently smaller than **6.5** as it cannot find this exact value in that range and we put **-1 **in this regard. Thus we get **x1 **as **5**.

A similar formula is used several times in this section. When we need a value adjacently larger than **6.5**, we used ‘**1**’ instead of ‘**-1**’ in the formula.

- Hit
**ENTER**to see the result in cell**F7**.

- Now type the following formula in cell
**F8**.

`=XLOOKUP(C14, B5:B12,B5:B12,,1,1)`

- Hit the
**ENTER**key and you will see a larger value than**6**in cell**F8**.

- After that, type the following formula in cell
**F9**.

`=XLOOKUP(C14, B5:B12,C5:C12,,-1,1)`

- Hit
**ENTER**. This operation will deliver you the value in cell**C9**.

- Then type the formula in cell
**F10**.

`=XLOOKUP(C14, B5:B12,C5:C12,,1,1)`

- Hit
**ENTER**and you will see the**Y Coordinate**of cell**C10**.

- After that, select cell
**C15**and type the formula given below.

`=FORECAST(C14,F9:F10,F7:F8)`

- Press the
**ENTER**key to see the**interpolated value**in cell**C15**.

Thus you can **interpolate **between two values within a small range.

**Read More:** **How to Do VLOOKUP and Interpolate in Excel (6 Ways)**

**3. Applying INDEX and MATCH Functions with FORECAST Function to Interpolate Between two Values**

We can also **interpolate **between two values within a small **range **of the dataset by using the **INDEX** and **MATCH** functions to extract the **coordinates** in the **range **and **interpolate **a value within them. Suppose we want to **interpolate **the value **6** in **B9:C10**. Let’s discuss the procedure below.

**Steps:**

- First, make some modifications in the dataset to place the
**coordinates**.

- Type the following formula in cell
**F7**.

`=INDEX(B5:B12,MATCH(C14,B5:B12,1))`

Here the **MATCH **function returns the position of the cell value of **C14 **in the **range B5:B12**. And then the **INDEX **function returns the **value **of that position in **B5:B12**. Thus it returned **x1**.** **

A similar formula is used in this section several times to determine **x2**,** y1, **and **y2**.

- Hit
**ENTER**to see the result in cell**F7**.

- Now type the following formula in cell
**F8**.

`=INDEX(B5:B12,MATCH(C14,B5:B12,1)+1)`

- Hit the
**ENTER**key and you will see the larger value than**6**in cell**F8**.

- After that, type the following formula in cell
**F9**.

`=INDEX(C5:C12,MATCH(C14,B5:B12,1))`

- Hit
**ENTER**. This operation will deliver you the value in cell**C9**.

- Then type the formula in cell
**F10**.

`=INDEX(C5:C12,MATCH(C14,B5:B12,1)+1)`

- Hit
**ENTER**and you will see the**Y Coordinate**of cell**C10**.

- After that, select the cell
**C15**and type the formula given below.

`=FORECAST(C14,F9:F10,F7:F8)`

- Press the
**ENTER**key to see the**interpolated value**in cell**C15**.

Thus you can **interpolate **between two values within a small range.

**4. Interpolating Between Two Values Utilizing a Mathematical Formula **

Another effective method to **interpolate **between two values will be to apply a mathematical formula. The interpolation formula is given below.

This is an equation of a straight line. Let’s follow the necessary instructions to apply it to **interpolate **between two values.

**Steps:**

- Make some modifications in the dataset for
**interpolation value**and type the following formula in cell**C15**. Here we want to find the**interpolated value**when the**X Coordinate**is**75**. And for this reason, we are going to take**X Coordinates**which are adjacently smaller or greater than**2.75**and their corresponding**Y Coordinates**in this dataset.

`=C7+(C14-B7)*(C8-C7)/(B8-B7)`

The formula returns the **interpolated **value by measuring the **slope **of the **2 **points which are **(2.5, 4) **and **(3, 6)**.

- Now just hit
**ENTER**to see the**interpolated value**in cell**C15**.

Thus you can **interpolate **between two values just by using a mathematical equation.

** (6 Methods)****5. Interpolation between Two Values by SLOPE and INTERCEPT Functions**

One of the easiest ways to **interpolate **between two values is to use Excel **SLOPE** and **INTERCEPT** functions and use their results into a **straight-line **formula. Let’s see the procedure below. We want to **interpolate **the **X Coordinate **10.

**Steps:**

- Make some changes in your dataset to store the
**slope**.

- Type the following formula in cell
**E7**

`=SLOPE(C5:C12,B5:B12)`

The **SLOPE **function returns the **slope/gradient **of the linear regression line which is made by the points formed by given **X **and **Y Coordinates**.

- Hit
**ENTER**and you will see the**slope**of these data in cell**E7**.

- Now type the following formula in cell
**E9**to find the**Y-intercept**.

`=INTERCEPT(C5:C12,B5:B12)`

The **INTERCEPT **function returns the **Y-intercept **of the linear regression line which is made by the points formed by given **X **and **Y Coordinates**.

- Hit
**ENTER**to see the output in cell**E9**.

- Insert this formula in cell
**C15**.

`=E7*C14+E9`

The formula is a basic straight line formula which is **y=mx+c**.

- Hit
**ENTER**to see the**interpolated**value in cell**C15**.

Thus you can determine the **interpolated **value between two values by using Excel **SLOPE **and **INTERCEPT **functions.

**6. Using GROWTH Function for Nonlinear Interpolation**

The **GROWTH **function is a special function to **interpolate **non-linear data. Our dataset basically consists of non-linear relations between **Y **and **X Coordinates**. So it would be best to use this function.

**Steps: **

- Make some changes to store the
**interpolated**We want to**interpolate**a value between**5**and**8**. Let it be**6.5**.

- Type the following formula in cell
**C15**.

`=GROWTH(C5:C12,B5:B12,C14)`

Here the **GROWTH **function returns the **interpolated **data by predicting exponential growth of the **X **and **Y Coordinates**.

- Hit
**ENTER**and you will see the**interpolated**value in cell**C15**.

Thus you can find **interpolated **values by using the **GROWTH **function. As this function works for non-linear relations, you can have more accurate data as a result of its help.

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

## Practice Section

In the following image, you will see the dataset of this article. I put this in so that you can practice on your own.

## Conclusion

The bottom line is, that this article will help you understand how to **interpolate **between two values in Excel. By **interpolation, **you can determine the exact or most accurate result for data that is not included in an experiment which is really important in scientific and statistical affairs. If you have any better methods of **interpolating **between two values in Excel, please leave them into the comment box. And also, share your feedback on my article. This will help me enrich my upcoming articles.