Standard deviation bars show how much your data typically varies

Standard deviation bars (also called error bars) are vertical lines attached to each data point in an Excel chart that show the range of typical variation in your data. If your chart shows average sales by month, error bars let you see at a glance whether some months had wildly different results or stayed fairly consistent. Excel calculates the standard deviation for you and draws the bars automatically once you tell it to.

The process takes about three steps: create a chart from your data, select the data series (the line or bars themselves), then add error bars and set them to display standard deviation. You do not need to calculate standard deviation separately — Excel handles that part.

Key Takeaways

  • Error bars must be added to an existing chart; you cannot add them to raw data in a spreadsheet.
  • Right-click the data series (the bars or line in your chart) and select "Format Data Series" to access error bar options.
  • Choose "Standard Deviation" from the error bar type menu, and Excel automatically calculates and displays the range for each point.
  • You can adjust the multiplier (usually 1, 2, or 3 times the standard deviation) to show more or less variation.

Create or open a chart first

Error bars only work on charts, not on spreadsheet cells. If you already have a chart, skip to the next section. If you need to create one, select the data you want to chart (including headers), then go to the Insert tab and click Chart. Choose the chart type that fits your data — column charts and line charts work best with error bars.

Once your chart appears, you can add error bars to it. The chart does not need to be perfect yet; you can adjust colors, labels, and other details after the error bars are in place.

Right-click the data series to open formatting options

Click once on one of the bars or points in your chart to select the entire data series (all the bars or all the points should highlight). Then right-click and select "Format Data Series" from the menu that appears. A panel or dialog box will open on the right side of the screen (in newer Excel versions) or as a separate window (in older versions).

Look for an option labeled "Error Bars" or a small bar chart icon in the formatting panel. Click it to expand the error bar options.

Set error bars to standard deviation

In the error bar section, you will see a dropdown menu with options like "Fixed Value", "Percentage", "Standard Deviation", and others. Click on "Standard Deviation". Excel will immediately draw vertical lines on your chart extending above and below each data point.

By default, Excel sets the error bars to show one standard deviation (1σ). This means roughly 68 percent of your data falls within those bars if your data follows a normal distribution. You can change this multiplier if you want to show a wider or narrower range — for example, entering 2 will show two standard deviations, which captures roughly 95 percent of typical variation.

Adjust the multiplier if needed

Look for a field labeled "Value" or "Multiplier" in the error bar options. The default is usually 1.0. If you want the bars to extend further (showing more variation), increase this number to 2 or 3. If you want them closer to the data points, decrease it to 0.5.

The choice depends on what you are trying to show. One standard deviation is common for showing typical variation. Two standard deviations is useful if you want to highlight outliers or show a wider confidence range. There is no single "correct" choice — it depends on your data and your audience.

Customize the appearance of the bars

Once the error bars are in place, you can change their color, thickness, and cap style. In the formatting panel, look for options like "Line Color" or "Line Style". You can make the bars match your chart colors or make them stand out, depending on what you want to emphasize.

You can also remove the horizontal caps at the top and bottom of each bar if they look cluttered. Look for a "Cap" option and set it to "No Cap" if you prefer a cleaner look.

Frequently Asked Questions

Can I add different error bars to different data series in the same chart?

Yes. Click on one data series, add and format its error bars, then click on a different data series and repeat. Each series can have its own error bar settings, colors, and multipliers. This is useful when comparing datasets with very different levels of variation.

What is the difference between standard deviation and standard error?

Standard deviation shows how spread out individual data points are. Standard error shows how much the average itself might vary if you repeated your measurement. Excel offers both options in the error bar menu. Use standard deviation to show variation in your actual data; use standard error if you are comparing averages across groups.

Why do my error bars look uneven or asymmetrical?

This usually means your data is skewed or has outliers. Standard deviation bars are always symmetrical around the average, so if they look lopsided, your actual data points are probably clustered on one side. This is normal and accurate — it reflects what your data actually shows.

Can I add error bars to a pie chart or doughnut chart?

No. Error bars only work on charts with numerical axes, like column, bar, line, and scatter charts. Pie and doughnut charts do not support error bars because they show parts of a whole rather than measured values.

How do I remove error bars after I have added them?

Right-click the data series again, select "Format Data Series", find the error bar section, and look for a button or dropdown that says "None" or has an X icon. Click it to remove the error bars. You can always add them back later using the same process.