The OST files are smaller than the PST files, as it doesn't download and store emails like the PST file. Even when the OST file is in huge in size, Remo Convert OST to PST software work without any limitation. The software works irrespective of file size. The software also allows selecting OST file manually or we can use built-in search tool to find the OST file. Even the demo version of Remo Convert OST to PST software has no limitation to file size.