Set the field size

You can adjust the amount of space that each record in a table uses by changing the field size property of number fields in the table. You can also change the field size of a field that stores text data, although this action has a smaller effect on the amount of space that is used.

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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    When you change the field size, the size of new data values is limited for the field. For number fields, the field size determines exactly how much disk space Microsoft Office Access uses for each value of the field. For text fields, the field size determines the maximum amount of disk space that Access will allow for each value of the field.
  • If the field contains data    When you change the field size, Access truncates all the values in the field that exceed the specified field size, and also limits the size of new data values for the field, as described above.

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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. For more information, see the See Also section.

  1. Right-click the table that contains the field that you want to change, and then click Design View.
  2. In the table design grid, select the field for which you want to change the field size.
  3. In the Field Properties pane, on the General tab, enter 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 that replication is not supported using the .accdb file format.
    • Decimal — For numeric values that range from -9.999... x 1027 to +9.999... x 1027. Storage requirement is 12 bytes.

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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. For more information, see the See Also section.

  1. Right-click the table that contains the field that you want to change, and then click Design View.
  2. In the table design grid, select the field for which you want to change the field size.
  3. In the Field Properties pane, on the General tab, enter 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.

 Note   For data in a Text field, 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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Applies to:
Access 2007