Scale bars provide a visual indication of the size of features, and distance between features, on the map. A scale bar is a line or bar divided into parts. It is labeled with its ground length, usually in multiples of map units, such as tens of kilometers or hundreds of miles. When a scale bar is added to the layout, it is associated with a map frame and maintains a connection to the map inside of the frame. Even if the map scale changes, the scale bar remains correct.
Insert a scale bar
When a scale bar is added to the page, it will be automatically associated with the default map frame. If there isn't a map frame on the page, the map frame will default to <None>. This property is not final, though, and can be modified anytime after the scale bar is inserted.
On the Insert tab, in the Map Surrounds group, click the New Scale Bar . Clicking the top half of the button will insert a default scale bar. Clicking the bottom half of the button will display a gallery of scale bar style items from any referenced styles. Choosing a style item will insert a scale bar with those properties.
Modify a scale bar
You can modify a scale bar's properties and appearance using contextual tabs on the ribbon and the Format Scale Bar pane. The following properties are available for scale bars and can be found on the Design contextual tab.
You can change the map frame a scale bar is associated with, from the drop-down list in the Map Frame group.
You can control the behavior of the scale bar when it is resized, or when the map scale changes, by choosing one of the following options from the Resize Behavior drop-down list in the Divisions group:
- Adjust width—Preserves the division value and number of divisions, and adjusts the scale bar width if the map scale changes.
- Adjust division value—Preserves the number of divisions and tries to preserve the scale bar width by adjusting the division value.
- Adjust number of divisions—Preserves the division value and tries to preserve the scale bar width by adjusting the number of divisions.
- Adjust divisions and division value—Preserves the number of subdivisions and tries to preserve the scale bar width by adjusting the number of divisions first, then the division values.
In the Divisions group, you can set division and division values for the scale bar. Certain buttons may be disabled depending on the current resize behavior. Division Value sets the value of one division, Divisions sets the number of divisions, Subdivisions sets the number of subdivisions, and checking Show one division before zero will update the scale bar to show one division before the zero mark.
In the Units group, you'll find controls to change the units the scale bar uses as well as how they are displayed. Units sets the units the scale bar will use, Label Position sets the position of the units label relative to the scale bar, and Label controls how the unit value is displayed.
The Marks group contains controls to set the tick mark properties. Frequency sets the number and location, and Position sets their position relative to the bar.
The Numbers group contains controls to modify the properties of the scale bar value labels. Frequency sets the number and location of values along the bar, and Position sets their position relative to the bar.
To modify the scale bar's appearance, use the controls available on the Format contextual tab. For more information about working with the Format tab, see Add and modify graphics and text.
Scale bar properties
Additional properties for the scale bar can be set by right-clicking the scale bar in the Contents pane and choosing Properties. In the Format Scale Bar pane there are general options to rename the scale bar, toggle on or off its visibility on the layout, or lock it so it cannot be selected on the layout.
You can also change the map frame that the scale bar is referencing. This is particularly useful when you have multiple map frames on your layout. The Map Frame drop-down menu shows the current selected map frame and all other map frames on the layout.
Map scales are often an average and can vary based on coordinate system, latitude, direction, and map extent. Compute at center calculates the map scale by using the center of the map frame. This scale can differ from the scale in the map view, which in many cases calculates the scale at a location along the equator. To enable Compute at center, click the checkbox.