# Adding error bars

Usually used in statistical or scientific data, error bars show a potential error or degree of uncertainty relative to each data market in a series.

Error bars are appropriate for the area, bar, column, line, and XY charts only.

To add error bars, do the following:

** 1. ** Select a data series, Excel displays the **Chart Tools**, adding
the **Design** and **Format** tabs:

** 2. ** Under **Chart Tools**, on the **Design** tab, in the **Chart Layouts** group, click
the **Add Chart Element** icon and choose the **Error Bars** list:

Excel proposes several error bars. Also, you can use **More Error Bars Options...**. If necessary, you
can fine-tune the error bar settings from the **Format Error Bars** pane:

In the **Format Error Bars** pane you can choose:

- In the
**Direction**group:**Both**Shows the actual data point value plus and minus a specific error amount**Minus**Shows the actual data point value minus a specific error amount**Plus**Shows the actual data point value plus a specific error amount

- In the
**End Style**group:**No Cap**Display error bars without end caps**Cap**Displays error bars with end caps

- In the
**Error Amount**group, Excel enables you to specify several types of error bars:**Fixed value**Uses the constant value that you specify in the**Fixed value**box to calculate the error amount for each data point and displays this error amount in the same height for Y error bars and the same width for X error bars.**Percentage**Uses the percentage that you specify in the**Percentage**box to calculate the error amount for each data point as a percentage of the value of that data point. Y error bars and X error bars that are based on the percentage of the value of the data points vary in size.**Standard deviation(s)**Displays the standard deviation for the plotted values that are calculated for each data point and then multiplied by the number that you specify in the**Standard deviation(s)**box. The resulting Y error bars or X error bars are the same size and do not vary with each data point.**Standard error**Displays the standard error amount for all plotted values. All data points in the series display the error amount in the same height for Y error bars and the same width for X error bars.**Custom**Uses values in a worksheet range that you specify as error amounts. Using this option, you can include formulas in the worksheet range when calculating the error amounts.

See also this tip in French: Ajouter de barres d’erreur.