# Calculating the magnetic course for a path

The Magnetic Course Calculator function calculates the magnetic course and distance between two specified points. This tool can be used to obtain the distance between two bearings based on the magnetic variation values for a particular year.

Steps:
1. Start ArcMap.
2. On the menu bar, click Customize > Toolbars > Production Feature Builder.
3. Click the Launch Feature Builder button on the Production Feature Builder toolbar.

The Feature Builder window appears in ArcMap.

 The Feature Builder window

Tip:

The Feature Builder window can be placed anywhere in ArcMap, or in the TOC, with the aid of the arrows showing the possible placement positions.

4. Choose Magnetic Course Calculator in the list on the Functions tab.
5. Define a coordinate for the start point of the polyline by doing one of the following:
• Clicking the Pinprick button on the Production Feature Builder toolbar, then clicking on the map
• Typing the coordinates in the cells on the Input tab in the Coordinates area
Tip:

To view the input coordinates on the map, double-click the row headers for each coordinate.

6. Repeat step 5 to define a coordinate for the ending point of the course leg.
7. If necessary, click the cell next to MagVar Value and type a value for the magnetic variation.

This can be a specified value or from a field defined in the MagVar Source parameter. The default unit is degrees.

8. Tip:

You can right-click the parameter name and change the unit of measurement. If you change the unit of measurement after defining a value, the value is converted to the new unit of measurement, and you may need to redefine the value.

9. If necessary, click the drop-down arrow next to MagVar Source and choose a source for the magnetic variation.

This is the source of the magnetic variation value.

10. If necessary, click the drop-down arrow next to MagVar Year and choose a different year for the World Magnetic Model.

This is the year associated with the magnetic variation value.

11. Click the Execute button .
12. Click the Output tab in the Functions area.

The magnetic course and distance values are displayed.

The magnetic course is the angle from the first coordinate to the second coordinate. The distance value represents the distance between the first coordinate and the second coordinate.

Tip:

You can right-click the parameter name and change the unit of measurement. If you change the unit of measurement after defining a value, the value is converted to the new unit of measurement, and you may need to redefine the value.

7/31/2012