What is the extension for Quicken data & backup files?

Quicken has changed the extension names at least 3 times over the years. There's a set of 3 or 4 files that constitute a Quicken account. The current set (not the backup) is usually located in the Quicken folder on C: drive, and is named as follows (depending on your version):

qdata.qdf (this is the main file with all your data in it)

qdata.qsd

qdata.qel

qdata.qph

So if you're manually backing up or copying the files be sure to get all 3 or 4.

The backup files that Quicken creates are put in a folder called "backup" inside the Quicken folder on the C: drive (I think by default). They are also a 3 or 4 file set with the same extensions as above. But Quicken will name them by number sequentially - such as:

qdata01.qdf

qdata01.qsd

qdata01.qel

qdata01.qph

Then the next backups will be a set called qdata02, the next a set called qdata03, etc.

Good luck,

Donk