Dell:

In order to calculate your password you need to find your service tag. Your service tag will usually be displayed on the locked screen of the computer in question.

BIOS Service Tags:

Dell BIOS service tags are 7 characters long with a 4 character suffix.
An example service tag for a Dell BIOS would be QZ6X56H-595B.

Other suffixes include D35B, A95B and 2A7B

Click here to calculate your BIOS password

HDD (Hard Drive) Service Tags:

Dell HDD service tags are 11 characters long with a 4 character suffix or padded from the left with ** or *** followed by 9 or 8 characters and a 4 character suffix.
Example service tags for a Dell HDD would be A79V4B7416H-2A7B or **0DFF3339H-595B.

Other suffixes include D35B and A95B

Click here to calculate your HDD password