How To: Calculate field values from an existing field to a new field in ArcMap


The instructions provided below describe how to calculate values from an existing field to a newly created field using the Add Field and Field Calculator tools in ArcMap.


A. Use the Add Field geoprocessing tool to create a new field.

  1. Launch ArcMap.

  2. In the Catalog window, navigate to Toolboxes > System Toolboxes > Data Management Tools > Fields > and launch the Add Field tool.
  3. Specify the necessary parameters to add the new field; pay attention to the field name and type to ensure the future calculated values are accepted.

For more information on field data types, refer to the following document: ArcGIS Help: ArcGIS field data types.

  4. Click OK to run the tool and add the field.

B. Use the Field Calculator to calculate values from an existing field to the new field.

  1. Right-click the layer or table to be edited and open the attribute table.
  2. Right-click the field heading for the field that was added above, and click the Field Calculator.

  3. In the Field Calculator, use the Fields list and Functions to build a calculation expression. In this case, add the field containing the values to be copied over to the new field to enable the name to display in the expression block.

  4. Click OK to run the tool.

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