How to Add a Trendline to a Google Sheets Chart

To add a trendline in Google Sheets, click or double-click the chart, open Customize > Series in the Chart editor, choose the data series under Apply to, and check Trendline. You can then choose a fit type and, if useful, display its equation or R-squared value.

What a trendline shows

A trendline is a line fitted to a chart series to make its overall direction easier to see. It can help reveal a broad rise, fall, or curve when individual data points vary from one period to the next. For example, monthly website visits might jump during a promotion and dip afterward; a trendline can make the longer-term direction more apparent than any one month does.

A trendline is a summary of the data, not a line connecting every observation and not proof of what caused a change. It also does not automatically make a forecast reliable. The line reflects the series and the fit type you choose, so interpret it alongside the data and the circumstances behind it.

Add a trendline step by step

Select the data you want to chart, or select a cell within an existing data range.
Choose Insert > Chart if you are starting from scratch. Sheets inserts a chart and opens the Chart editor. For an existing chart, double-click it to open the editor.
In the editor, open Customize, then expand Series.
If the chart contains several series, use Apply to to select the series you want. This matters because a trendline applies to a series, not automatically to every series in the chart.
Check Trendline. Use the controls that appear to select a type, adjust its label, and change its appearance.

The chart updates as you change these settings. If the Trendline option is missing, first check whether the selected chart type supports trendlines and whether the series is available to customize. Switching to a scatter, line, column, or bar chart is a practical way to check; a pie chart, for example, is not a useful chart for fitting a trendline.

Choose a chart that fits the data

For a relationship between two numeric variables, a scatter chart is usually the clearest starting point. Put the independent or input values in one column and the measured values in the next, select both columns, and insert a scatter chart. The first column supplies the horizontal values and the second supplies the plotted series. A scatter chart places points according to numeric x-values, so unequal intervals are represented as unequal distances.

For values arranged by date or category, a line chart can make a time pattern easier to follow. Column and bar charts can be useful when comparing amounts across categories. Google Sheets offers trendlines for common chart types such as scatter, line, column, and bar charts, although the available controls can depend on the chart and series. If you need to analyze a relationship between numeric x and y values, prefer scatter over a category-based chart.

Check the chart’s setup before interpreting the line. Confirm that the intended column is the series and that the horizontal axis contains the values or dates you expect. If Sheets has treated a row of numbers as labels, or used the wrong column as the series, the fitted line may be mathematically consistent with the chart but answer the wrong question.

Pick a trendline type

The best fit type depends on the shape of the relationship and the context of the data. Google Sheets provides several choices in the Series trendline settings:

Linear: A straight line that summarizes a roughly steady increase or decrease. It is a sensible first choice for a pattern that changes by a similar amount across the range.
Exponential: A curved fit for a pattern that changes at a rate proportional to its current level, such as some forms of rapid growth or decay. It is not suitable for every data set, especially when the values do not fit the model’s requirements.
Polynomial: A curve that can capture bends in the data. The degree setting controls the curve’s complexity; a higher degree can follow more changes, but may also follow random fluctuations rather than a meaningful pattern.
Logarithmic: A curve that can rise or fall quickly at first and then level off. Consider whether that shape makes sense for the quantities being measured.
Power series: A curved relationship used when one quantity changes as a power of another. As with other non-linear fits, it should be chosen because it suits the question, not simply because it makes the line look closer to the points.

Start with the simplest model that plausibly describes the relationship. A curved fit can make a chart look more precise, but a complicated line is not automatically more informative. If different fit types tell very different stories, treat that as a reason to investigate the data and assumptions rather than selecting whichever line looks most persuasive.

Show the equation and R-squared

In the trendline controls, the Label setting can show the fitted equation on the chart. This is useful when you want to document the line or use its form in a separate calculation. The displayed equation describes the selected trendline and should not be mistaken for the original observations or a guarantee that future values will follow the same pattern.

Sheets can also display the R-squared value, commonly written as R². It is a measure of how closely the fitted line accounts for variation in the plotted data under the selected model. A value closer to 1 indicates a closer fit for that data set; it does not prove that the model is appropriate, that one variable causes another, or that predictions beyond the observed range will be accurate. Compare R² values cautiously, especially when comparing different fit types or data sets.

For example, suppose a scatter chart compares weekly advertising spend with weekly site visits. A linear trendline can summarize whether visits generally rise with spend. A high R² would indicate that the line fits those plotted points relatively closely, but it would not establish that advertising alone caused the visits: seasonality, promotions, or other changes could also matter.

Format the line and keep the chart readable

Trendline formatting is available alongside its type and label settings in Customize > Series. You can adjust the line’s color, opacity, thickness, and dash style. Choose a color that contrasts with the data series without competing with it. If the chart already has several colored lines, a neutral or clearly distinct trendline style can prevent readers from confusing the fit with another measured series.

Make the chart title and axis labels specific enough to explain what is being measured and in what units. If you show the equation or R², keep it positioned so it does not cover points or labels. A chart with too many series, labels, or fitted lines can obscure the pattern it is meant to clarify. If necessary, make a copy of the chart and use one version to show the series and another to focus on the trend.

Common problems and how to fix them

Trendline is unavailable: Open the chart editor’s Series section and confirm the correct series is selected. If the option still does not appear, try a supported chart type such as scatter, line, column, or bar.
The line looks unrelated to the points: Check the chart’s data range, series, and horizontal axis. For a relationship between two numeric columns, use a scatter chart and make sure the x-values are in the first selected column.
The curve changes dramatically when you change its type: Different models make different assumptions. Use the subject matter and the data pattern to choose a fit; do not rely on appearance alone.
The equation or R² is missing: Reopen the trendline settings and check the Label selection or the R² display option. These settings are part of the selected series’ trendline controls.
The line does not account for every point: That is expected. A trendline summarizes a pattern; it is not designed to pass through every observation.

Also inspect the source data for blank cells, text stored where numbers should be, duplicate records, and inconsistent date intervals. These can affect what appears in the chart or make the pattern harder to interpret. A trendline cannot repair inaccurate or incomplete source data.

Trendlines versus connecting lines and forecasts

A line connecting points shows the sequence of observations. A trendline instead fits a model to the series and may not pass through any particular point. These lines answer different questions: connecting lines emphasize the path between recorded values, while a trendline emphasizes the overall fitted pattern.

A trendline is also not the same thing as a full forecasting method. Extending a fitted relationship beyond the data can be tempting, but the pattern may change, and the uncertainty generally grows farther from the observations. Use a trendline to describe the charted data unless you have a sound reason and suitable method for forecasting. For important planning decisions, consider the data quality, assumptions, and other relevant factors rather than relying on the visual line alone.

Frequently Asked Questions

Can I add a trendline to every Google Sheets chart?
No. Trendlines are available for supported chart types and series, not every chart. If the Trendline control is absent, check the chart type and select the intended series. A pie chart, for example, does not show a numeric relationship that a fitted trendline can summarize.

How do I add a trendline to only one series?
Open the chart editor, go to Customize > Series, select the desired series under Apply to, and check Trendline. Repeat for another series only if you specifically want a separate fit for it.

Which trendline should I use?
Use a linear fit for a roughly straight pattern. Consider exponential, polynomial, logarithmic, or power series fits only when the shape and context support them. A more complex model can fit the observed points closely without being a better explanation or forecast.

What does R-squared mean on a Google Sheets chart?
R² indicates how closely the chosen fitted model accounts for variation in the plotted data. A high value is not proof of causation, correctness, or reliable predictions outside the observed range.

Can I add a trendline in the Google Sheets mobile app?
The steps here are for Google Sheets in a web browser on a computer, where the Chart editor provides the Series trendline controls. If those controls are not available in your app, open the spreadsheet in a desktop browser to edit the chart.

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