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Set the field size

Applies to: Access for Office 365, Access 2019, Access 2016, Access 2013, Access 2010, Access 2007.

You can revise the amount of space that each record in an Access table uses by modifying the field size property of number fields in the table. You can also differentiate the field size of a field that stores text data, although this action has a minute effect on the amount of space that is used.

Note: The functionality explained in this article doesn’t apply to Access web databases and Access web apps.

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What happens when I change the field size?

You can change the field size of a field that is empty or that already contains data. The effect of changing the field size depends on whether the field already contains data.

  • If the field does not contain data – After you change the field size, the size of new data values is constrained for the field. For number fields, the field size enforces exactly how much disc space Access uses for each value of the field. For text fields, the field size determines the maximum amount of disk space that Access allows for each value of the field.

  • If the field contains data  –  Once you alter the field size, Access truncates all the values in the field that exceed the specified field size, and also restricts the size of new data values for the field, as described above.

Change the field size of a number field

Tip: If the field for which you want to change the field size already contains data, consider making a backup of your database before you proceed.

  1. In the Navigation Pane, right-click the table that includes the field that you want to change, and then press Design View.

  1. In the table design grid, confirm the field for which you want to change the field size.

  1. In the Field Properties pane, on the General tab, state the new field size in the Field Size property. You can choose from the following values:

  • Byte — For integers that range from 0 to 255. Storage requirement is a single byte.

  • Integer — For integers that range from -32,768 to +32,767. Storage requirement is two bytes.

  • Long Integer — For integers that range from -2,147,483,648 to +2,147,483,647. Storage requirement is four bytes.

Tip: Use the Long Integer data type when you create a foreign key to relate a field to another table’s AutoNumber primary key field.

  • Single — For numeric floating point values that range from -3.4 x 1038 to +3.4 x 1038 and up to seven significant digits. Storage requirement is four bytes.

  • Double — For numeric floating point values that range from -1.797 x 10308 to +1.797 x 10308 and up to 15 significant digits. Storage requirement is eight bytes.

  • Replication ID — For storing a GUID that is required for replication. Storage requirement is 16 bytes.

Note: Replication is not supported using an .accdb file format.

  • Decimal — For numeric values that range from -9.999… x 1027 to +9.999… x 1027. Storage requirement is 12 bytes.

Change the field size of a text field

Tip: If the field for which you want to change the field size already contains data, consider making a backup of your database before you continue.

  1. In the Navigation Pane, right-click the table that has your specific field that you seek to change, and then click Design View.

  1. In the table design grid, pick the field for which you want to change the field size.

  1. In the Field Properties pane, on the General tab, typen the new field size in the Field Size property. You can enter a value from 1 to 255. This number specifies the maximum number of characters that each value can have. For larger text fields, use the Memo data type (Long Text if using Access 2016).

Note: For data in a Text field (Short Text if using Access 2016), Access does not reserve space beyond what is necessary to hold actual values. The Field Size property is the maximum field value size.

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