To convert an Outlook OST file to a Gmail account, use SysInspire OST to PST Converter Tool. This tool gives top-of-the-line features to its consumers. It supports OST file data conversion to PST and a variety of other formats, including vCard, EML, Zimbra, HTML, MBOX, Gmail, Yahoo, Office 365, MSG, ICS, and EMLX. With the email filtering feature, you can convert only a subset of critical OST files based on a date range. From SysInspire's official website, you may get a free demo version of this utility.
Read More:- Convert OST File to PST