How to Calculate Slope in Excel

In this article, we will learn to calculate the slope in Excel. 

Finding slope using Excel function

Les us try to calculate the slope using simple formula's by using the coordinates of 2 points. First write the coordinates of 2 points:

slope coordinates

Calculate difference beteween x coordinates: C5-C4

Calculate difference beteween coordinates formula

The result is 2 in this example.

Calculate difference beteween coordinates result

Now let us calculate difference between y coordinates: D5-D4

Calculate difference beteween y coordinates formula

The result is 2 again.

Calculate difference beteween y coordinates result

Slope will be difference of Y coordinates divided by difference of X coordinates:

difference of Y coordinates divided by difference of x coordinates

The Slope here is 1.

difference of Y coordinates divided by difference of x coordinates result

This was very simple approach, now we will do the same by using the slope function inbuilt in Excel:

SLOPE(known_y's, known_x's)

The SLOPE function syntax has the following arguments:

  • Known y's Required. An array or cell range of numeric dependent data points.
  • Known x's Required. The set of independent data points.

SLOPE function

See in this example as we are typing the formula it is being guided by Excel with the comments below. The slope formula written as SLOPE(KNOWN Y’S,KNOWN X’S)

So the formula will be:

=SLOPE(D4:D5,C4:C5)

The final contents in the sheet with results is like: 

SLOPE function calculated

Please find attached the Excel file for reference.

Finding slope from the chart

There is no need to use slope formula to find the slope. Sometimes it might be possible to find it from the graph.

Lets assume we have such data.

slope values

There is a measurement of some value. And you need to find the slope for the value. How to do that?

First plot the line chart for that. Go to Insert – Line Chart.

slope insert line chart

You can see the simple chart.

slope line chart

Right click the line and choose Add Trendline.

slope add trendline

Menu pops in the right side of your screen. Choose "Display Equation on the Chart".

slope display equation for chart

And here is your slope.

slope in the chart

Can't you see that? If you forgot I will remind.

 

The equation of the trendline comes from the y = f(x) = ax + b

In this example y = 2.4706x – 10.941

a = 2.4706 and b = -10.941

a = slope = 2.4706

Note: b is the point where the line cross the horizontal line for x=0 point.

To continue pls check how to insert Slope Graph tutorial.