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. They extend above and below the point by one standard deviation — a measure of how spread out your numbers are. If your data points cluster tightly, the bars are short. If your numbers jump around a lot, the bars are tall.

You add them after you've already created a chart. Excel calculates the standard deviation for you; you just tell it to display the bars. This takes about three clicks once you know where to look.

Key Takeaways

  • Standard deviation bars attach to an existing chart and show how much variation exists in each data group.
  • You create the chart first (column, line, or scatter chart work best), then right-click the data series to add error bars.
  • In the error bar dialog, choose "Standard Deviation" from the dropdown menu instead of the default "Fixed Value" option.
  • The bars will extend one standard deviation above and below each point; you can change this to 2 or 3 standard deviations if you want wider bars.
  • Standard deviation bars work best when you have multiple measurements of the same thing — like test scores from five different classes, or sales figures from multiple store locations.

Create your chart before adding the bars

Standard deviation bars only attach to charts that already exist. Start by selecting the data you want to chart — usually a column of labels (like month names or group names) and one or more columns of numbers. Then go to the Insert tab and choose a chart type. Column charts and line charts are the most common choices for showing standard deviation.

Once your chart appears on the spreadsheet, click it to select it. You'll see the chart get a border and the ribbon will change to show chart-specific options. This is the moment to add the error bars.

Right-click the data series to open the error bar menu

Click directly on one of the bars or points in your chart — not on the background, but on the actual data. All the bars or points in that series will highlight slightly, showing they're selected. Right-click on the highlighted data and a menu will appear.

Look for an option that says "Format Data Series" or "Add Error Bars" depending on your Excel version. Click it. A dialog box will open with tabs along the left side.

Switch the error bar type from Fixed Value to Standard Deviation

In the error bar dialog, you'll see a section labeled "Error Amount" or "Display" with radio buttons or a dropdown menu. By default, Excel selects "Fixed Value," which means the bars extend by a number you type in (like 5 or 10). You need to change this.

Click the radio button or dropdown next to "Standard Deviation." Excel will when ready calculate the standard deviation of your data and set the bars to extend one standard deviation above and below each point. The preview in the dialog will update to show you what the bars will look like.

Adjust the multiplier if you want wider or narrower bars

Once you've selected Standard Deviation, you may see a field that says something like "1.0" or a percentage. This is the multiplier — it controls how many standard deviations the bars represent. A value of 1.0 means one standard deviation. A value of 2.0 means two standard deviations (wider bars, covering more of your data range).

For most purposes, 1.0 is the standard choice. But if you want the bars to cover a wider range — to show where roughly 95% of your data falls instead of 68% — change it to 2.0. Leave it at 1.0 unless you have a specific reason to change it.

Click OK to explore the bars to your chart

Once you've set the error bar type to Standard Deviation and chosen your multiplier, click the OK button. The dialog will close and your chart will now display the bars extending from each data point.

If the bars don't look right — if they're too thick, too thin, or the wrong color — you can right-click them again and adjust their appearance. You can also delete them by selecting them and pressing Delete, then starting over if you made a mistake.

When standard deviation bars actually help you see what matters

Standard deviation bars are useful when you're comparing groups and want to show not just the average, but how consistent each group is. For example, if you're comparing test scores across five classrooms, the bars show which classrooms have consistent performance and which have wide variation. A classroom with short bars performed similarly across all students; a classroom with tall bars had some very high and some very low scores.

They're less useful if you only have one or two data points per group, because standard deviation needs multiple measurements to be meaningful. They're also less useful if your data is already sorted or filtered in a way that doesn't represent the full picture — the bars will only reflect what's in your chart, not what you left out.

Frequently Asked Questions

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

Yes. Click on one data series, add error bars to it, then click on a different series and add error bars separately. Each series can have its own settings. This is useful when you're comparing groups that have different amounts of variation.

What's the difference between standard deviation and standard error?

Standard deviation measures how spread out your individual data points are. Standard error measures how much your average might differ if you repeated the measurement. For most charts, standard deviation is what you want. Standard error is used when you're showing averages from multiple samples and want to indicate uncertainty in the average itself.

Why are my error bars showing as just dots instead of lines?

This usually means the bars are too small to see — either your data has very little variation, or your chart is zoomed in too far. Try changing the multiplier to 2.0 or 3.0 to make the bars wider. If that doesn't help, check that you actually selected Standard Deviation and not Fixed Value.

Can I remove the error bars without deleting the whole chart?

Yes. Click on the error bars themselves (the lines, not the data points), then press Delete. The bars will disappear but your chart and data stay intact. You can add them back later by right-clicking the data series again.