In Excel: click the chart, open the ➕ Chart Elements button and tick Trendline — then right-click the line ▸ Format Trendline to pick the type and show the equation and R².
On this page7
Build the chart first — trendlines attach to a series, not to a range. Scatter and line charts are the honest choices.
Click the chart, press the ➕ Chart Elements button and tick Trendline.
If the chart has several series, pick which one the trendline belongs to when Excel asks.
Right-click the trendline ▸ Format Trendline and choose the type: Linear unless you have a reason.
Tick "Display Equation on chart" and "Display R-squared value on chart" at the bottom of the pane.
Use the Forecast Forward box to extend the line past the data, and say in the chart title that the extension is a projection.
What this does
A trendline is a fitted line drawn through a data series: linear by default, with exponential, logarithmic, polynomial, power and moving-average alternatives in the Format Trendline pane. Two checkboxes at the bottom of that pane matter more than the line itself — "Display Equation on chart" and "Display R-squared value on chart". The equation lets you reproduce the fit in a formula, and R² tells you how much of the variation the line actually explains, which is the difference between a trend and a decoration. Excel also exposes the same maths as worksheet functions: SLOPE, INTERCEPT, RSQ, LINEST and TREND. Most people learn this as a sequence of clicks and forget it by next week; learning it as a pattern instead is what lets you apply it to the next, slightly different version of the problem without starting from scratch. That is the difference this page is trying to make. The difference between a quick fix and a sheet you can trust is the extra minute you spend validating “add trendline to excel chart”. Start on a copy or a tiny sample, keep the affected chart visible, and compare the result with the outcome you expected before you touch the real workbook. When a formula is involved, keep the inputs labelled beside it, reference cells instead of typing values, and apply number formatting only after the result checks out. The point is a visual that makes the number obvious at a glance, but the practical win is that someone else can open the file and understand what happened without asking you.
A worked example
Twelve months of revenue in B2:B13 against month numbers in A2:A13. Click the chart ▸ ➕ ▸ Trendline ▸ Linear. Right-click the line ▸ Format Trendline ▸ tick Display Equation and Display R-squared. If the chart shows y = 3,120x + 41,500 and R² = 0.87, revenue is rising about €3,120 a month and the straight line explains 87% of the variation. The same numbers without a chart: =SLOPE(B2:B13,A2:A13) returns 3120, =RSQ(B2:B13,A2:A13) returns 0.87. A trendline turns a scatter of points into a stated rate of change, and the equation plus R² is what makes that statement defensible instead of a line someone drew through the noise. Check the referenced cells, argument order and result type in your workbook. Start with the worked example before changing an input, then compare the changed result with the calculation you expected. An error value or a result of a different type is a reason to inspect the inputs and arguments.
In Google Sheets
Google Sheets support for this task has not been verified. Check the function, arguments and workflow in the target product before transferring the example. Matching formula notation does not establish identical behaviour. Nothing on this page is behind a login or a download: the exact answer is at the top, and the detail below it is there for when you need it. That is the whole promise here — the answer first, and just enough context to make it stick. For “add trendline to excel chart”, keep the input cells and the result visible while you check the formula in Excel. Follow the worked example and change one input at a time. The steps explain the workbook calculation; this page does not run a live calculator for that task.
Common mistakes
- Fitting a high-order polynomial because it hugs the points — an order-6 fit through 12 points has almost no predictive value and a flattering R².
- Adding a trendline to a bar chart of categories, where the x-axis has no numeric meaning.
- Quoting the slope without R², which hides how well the line actually fits.
- Forecasting far beyond the data and presenting the extension as a measurement rather than an assumption.
- Leaving unequal time gaps in the x values while treating them as evenly spaced — use a scatter chart with real x values.
Frequently asked questions
How do I add a trendline in Excel?
Click the chart, press the ➕ Chart Elements button and tick Trendline. On Mac use Chart Design ▸ Add Chart Element ▸ Trendline.
How do I show the trendline equation?
Right-click the trendline, choose Format Trendline, and tick "Display Equation on chart" and "Display R-squared value on chart" at the bottom of the pane.
What does R-squared mean?
The share of the variation in your data that the fitted line explains, from 0 to 1. R² = 0.87 means 87%. A low R² means the line is drawn but the relationship is weak.
Can I get the trend without a chart?
Yes — =SLOPE(known_ys, known_xs) and =INTERCEPT(known_ys, known_xs) give the same line, =RSQ() gives R², and =TREND() returns fitted values for new x inputs.
Other ways people ask this
On the way here you may have searched this as “add trendline in excel chart” and “trendline chart excel” — it is all the same task, and this page is the single, complete answer to it.
Why do people search for this in so many different ways?
Because the same task has many names. “add trendline in excel chart”, “trendline chart excel” all point at the one operation explained on this page, which is why they all lead here.