How To: Customize numeric data precision and scale in ArcMap


When adding a numeric field to a file or personal geodatabase attribute table, 'precision' refers to the number of significant digits that can be stored in a field, and 'scale' represents the number of decimal places.

The following workflow describes how to define the precision and scale for fields in ArcMap.


Setting the precision and scale when creating a new numeric field

The Add Field (Data Management) tool is used create a new field in the attribute table. It allows users to specify precision and scale values. However, these values are ignored if the selected field type does not match the precision and scale values entered.

Use the following guidelines to select the field type for a given precision and scale.

  • When creating a float, double, or integer field and accepting the default value '0' for Precision and Scale, the Add Field tool creates a binary type field if the underlying database supports binary data type. As personal and file geodatabases support only binary type fields, precision and scale are ignored.
  • When creating float and double fields and specifying a precision greater than six, use a double; otherwise, use a float. By default, when creating a double field and specifying a precision with a value of six or less, a float field is created. Likewise, creating a float field and specifying a precision greater than six creates a double field.
  • Specifying a field with a scale of '0' and a precision of 10 or less creates integer fields. Setting a precision of more than 10 when creating an integer field creates a double field.

Setting the precision and scale of numeric fields in tables

Sometimes, numeric values are truncated in the field. This is because the default number of decimal places that can be displayed in an attribute table is six. The number of decimal points and significant digits can be reviewed in Field Properties. Refer to ArcMap: Formatting numeric fields in tables for steps to do this.

Setting the scale during an editing session

When editing, ArcMap displays numerical values in three decimal places. These values include the values reported when new features are created, as well as distance, coordinates, and values found in Edit Sketch Properties. The number of decimal places displayed for measurements can be customized using Editing Options. Refer to ArcMap: Setting the number of decimal places displayed for measurements for more information.

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