Software & Apps MS Office Do Outlook PST Files Have a Size Limit? Keep your Outlook PST archive folder size small for best performance Share Pin Email Print @Lifewire MS Office Outlook Word Excel Powerpoint By Heinz Tschabitscher Writer A former freelance contributor who has reviewed hundreds of email programs and services since 1997. our editorial process Heinz Tschabitscher Updated June 24, 2019 All Microsoft Outlook versions use PST files to store email, contacts, calendar data, and other Outlook data. Over time, these files grow in size and, as these files become larger, Outlook performance takes a hit. Keep the PST file sizes small, either through deleting old information or archiving it, to keep Outlook performing at its best. Instructions in this article apply to Outlook 2019, Outlook 2016, Outlook 2013, Outlook 2010, and Outlook for Office 365. Do Outlook PST Files Have a Size Limit? Outlook uses a PST file format capable of storing Unicode data, a standard that represents most alphabets on computers. These PST files have no size limit, but a practical limit of 20 GB to 50 GB is recommended. How to Archive Older PST Items Automatically Use Outlook's AutoArchive feature to automatically move items to an archive to keep your folders and inbox under control. Start Outlook. Select File. Go to Info and select Account Settings. Select Account Settings. Go to the Data Files tab and select Add. In the File name text box, type the name of the archive. Select the Save as type dropdown arrow and choose Outlook Data File. Protect the file with a password. Select the Add Optional Password checkbox and follow the instructions. Select OK. Select Close. You may never need to access your archive files, but it isn't difficult to restore an Outlook PST archive. Change AutoArchive Settings for a Single Folder Change the settings of individual folders to suit your needs. Start Outlook. In the Navigation Pane, right-click the folder you want to change. Select Properties. Select the AutoArchive tab. Select the settings you want to apply, such as Do Not Archive Items in This Folder or Permanently Delete Old Items. Select Apply and then select OK to apply the changes and close the window.