How to Find Slopes in Google Sheets
Spreadsheet users often need to calculate the slope of a line related to the data in the spreadsheet. If you're a new user or used to using Microsoft Excel, it might be a little difficult to figure out how to do this yourself. Luckily, finding slopes in Google Sheets is an easy process that only takes a minute or so once you know what you're doing.
In this article, you'll learn to calculate slope values in Google Sheets with and without graphs.
What is slope?
First off, what exactly is a slope in Google Sheets?
Slope is a concept in geometry that describes the direction and steepness of a line on a Cartesian plane. (The Cartesian plane is the standard xy grid, which you may remember from math class having an X and Y axis.)
A line going up from left to right on a plane has a positive slope; a line going down from left to right has a negative slope.
In the image below, the blue line has a positive slope, while the red line has a negative slope:
The slope is expressed as a number that indicates how much a straight line rises or falls over a given distance (called Rise over Run).
Here is an example:
If the line goes from X=1, Y=0 to X=2, Y=1 (ie the line goes up +1 on the Y axis and +1 on the X axis at the same time), the slope is 1. If it goes from X=1, Y=0 to X=2, Y=2, the slope is 2, and so on.
A larger number means a steeper slope; a slope of +10 means a line goes up 10 on the Y axis for every unit moved on the X axis, while a slope of -10 means every unit moved on the Y axis, a line descends 10 on the Y axis and the X axis.
On spreadsheets, slope values are often associated with linear regression, a method of analyzing the relationship between two or more variables.
These variables consist of related Y values and independent X values, which will be stored as two separate table columns on the spreadsheet.
A dependent value is a value that changes automatically by counting, while an independent value is a value that can be changed freely. A typical example is one column (by X variable) containing a series of dates, and another column (by Y variable) containing numeric data, such as sales data for that month.
Where are the lines? Where are the graphs? The slope is about the way the line moves, right?
Think of spreadsheet data as plotting points for graphs. The data represented in this table can be easily visualized using a line chart.
How to Find Slopes in Google Sheets
Google Sheets provides a simple yet powerful set of tools for creating line charts from tabular data. In this example, all you have to do is select the entire data table (from A1 to B16) and click the "Insert Chart" button. Immediately after doing this, Sheets will generate the following chart:
Open Google Sheets and enter data. Then, click the More menu icon in the upper right corner.
Click the chart icon.
It goes down in some places and up in others! How are you supposed to calculate the slope of such a crazy line? The answer is something called a trend line. Trendlines are smoothed versions of lines that show the overall trend of numbers.
Click Edit Chart. It's also easy to get trendlines in a table.
Click on the trend line. In the chart editor that pops up, click the Settings tab and change the chart type to Scatter.
Click the Customize tab, open the Series drop-down section, and toggle Trendlines.
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Your graph should now look like this:
A light blue line along a series of points on a chart is a trendline.
So how do you find the slope of that line?
Well, if this is a math class, you're going to have to do some math. Fortunately, it's the 21st century, and math classes are way behind. Instead, we can tell the computer to do it for us. Thanks, Google.
How to Find the Slope of a Chart on Google Sheets
We can use Google Sheets to calculate the slope in the graph editor. Just follow these instructions to find the slope of any line graph in Google Sheets.
Select Label > Use Formula. This will add the equation that Google Sheets uses to calculate the trend line, the slope of our line is the part to the left of the *x term.
In this case, the slope is +1251. This means that for every month that passes, sales revenue increases by $1,251.
3. Interestingly, you don't actually need a graph to calculate the slope. Google Sheets has a SLOPE function that calculates the slope of any table of data without first plotting it as a picture. But drawing pictures is very helpful in learning how to do it all, which is why we do it.
4. Instead of creating a chart, you can add the SLOPE function to a cell in the spreadsheet. The syntax for the Google Sheets SLOPE function is SLOPE(data_y, data_x). This function will return the same slope value as in the chart equation.
Note that the order of entry is a bit backwards from how you might display information in the table. This is because Sheets expects you to put the independent data (sales revenue) first and the dependent variable (month) second.
You should also note that the SLOPE function is not as smart as the chart creator. It needs purely numeric data for the dependent variable, so we change these cells to 1 to 15.
Select any empty cell in the spreadsheet and enter "=SLOPE(b2:b16, a2:a16)" and hit Return.
And our slopes, which are more precise than the graphs provided.
final thoughts
This is how you can find the slope in Google Sheets. Hopefully these instructions will help you if you can't figure it out yourself.
If you prefer to use Excel instead of tables, there is also a TechJunkie guide for finding slope values in Excel.
Do you have an interesting application for finding slopes in Google Sheets? Share with us below!