Hopefully you have a Backup
OR
The Hard Drive from the old system
Then it is Easy-Peasy
https://manual.calibre-ebook.com/faq...ter-to-another
And the total time is just a Tad above the time to copy from Backup/Old To New.
If the OLD computer is dead and it was not the Hard Drive: Remove the old drive and put it in a USB Drive case (or use a Clone drive cable

) to allow the New PC to see it for the copy process.