How many documents are in your collection?
Point the estimator at your PSTs, Gmail/Takeout mbox exports, ZIPs, folders or loose files and it counts what a review platform would actually charge you for — every email, attachment and document, broken out by type, with exact duplicates identified the same way Lumios de-duplicates a case. All reading happens on this device; nothing is extracted to disk and nothing is uploaded.
Drop as many as you like, mixed freely — mailboxes, archives, whole collection folders, loose documents. A dropped folder shows up as one line in the report. Very large files are read in slices, so a 50 GB mailbox uses no more memory than a small one.
Your files never leave this device. The scan runs entirely in your browser — open your network tab and watch: zero uploads.