Create a Polynomial Trendline in Excel

When we talk about Excel Charts, there are limitless possibilities at our disposal for every data set type, or for any problem we may face.

There are a lot of options for trendlines as well. In the example below, we will show how to create one of them- a polynomial trendline.

Create a Polynomial Trendline in Excel

Polynomial Trendline is very useful when we want to present data that fluctuates. It is presented with a curved line.

There are different orders of the polynomial, which can be defined by the number of fluctuations in our data set, or, in simple terms, how many bends are appearing in the curve. Order 2 usually has one bend, order 3 has one or two bends, order 4 has up to three, and so on.

For our example, to create the chart with a polynomial trendline, we will use the list of different race times with athlete numbers for a half-marathon sprint:

For the next step, we will select the data, and then go to Insert >> Charts and choose the Scatter chart among the various options:

After we do this, we will have our chart created:

Various results are shown in the order of athletes’ numbers on the horizontal line.

For the next step, we will click on the dots that represent the times achieved. We can click on any dot, and then right-click and choose Add Trendline:

Once we click on it, we will immediately be presented with the Format Trendline window on the right side. We will choose the Polynomial option from Trendline Options:

And we will notice that we only have one curved line, which does not show us anything. For the trendline to work, we need to add orders (i.e. bends or so-called hills and valleys), until it looks like something sensible:

For our table, we need to go for Order 6 to achieve what we want. Once we do, we will get the sensible graph, as the picture above indicates.

Tomasz Decker is an Excel specialist, skilled in data analysis and financial modeling.