Incremental and Differential Backup

Posted by @AOMEI

June 1, 2017

These two options of incremental and differential backup are two advanced backup methods that can help to reduce backup time and storage space.

General Introduction

As time progresses, there will be more and more data and files stored on your system drive, data partitions, etc. In order to ensure data integrity, it is important to back up changed data regularly.

There are 3 options available:  Full Backup, Incremental Backup and Differential Backup. The following paragraphs describe the differences among them, and can help you decide your backup plan:


Tips: For a step-by-step guide with screenshots displaying how to perform an Incremental or Differential backup, please click here: How to Do Incremental and Differential Backup.

What Is the Difference between Incremental and Differential Backup

Full Backup

A full back up takes a snapshot of all the data on the selected folders, partitions or hard disks at the time the backup is performed, and saves it to an Image file. A full backup is always the basis of any incremental and differential backup. A Full Backup can be used to restore all the files and folders in its image, to the state when the image was created.

Once you have performed a Full backup, you can create Incremental and Differential backups. These are much quicker to create than a Full backup of the same data and the images created are smaller

Full Backup

Incremental Backup

An Incremental backup takes a snapshot only of the changed and newly added files based on the previous related backup, be it a full or incremental backup. Data that have not changed will not be backed up. Thus, the time and image storage required for incremental backup are both less than a full backup. A Full Backup must exist as the start point of a series of incremental backups. A typical set would be, in time sequence:

Full Backup, as basis

Incremental Backup 1
Incremental Backup 2
Incremental Backup n

All the image files of incremental backup series share a sequential relationship.

All data can be recovered to the state when any Incremental Backup was done, by recovering the parent Full Backup, followed in turn by each Incremental Backup in between.

If any one of the incremental image files in the sequence is damaged or missing, subsequent image files will be invalid.

"Full Backup + regular Incremental Backup" is the most commonly-used backup scenario.

Incremental Backup

Differential Backup

A Differential Backup is always directly related to its originating Full Backup. It will back up all data added and changed since the Full backup was done. Therefore, compared to full backup, the backup time and image file storage space are both less. If one of the differential backup image file becomes damaged or lost, it will not affect others.

All data can be returned to the state when the Differential Backup was done, by recovering the parent Full Backup, followed by the required Differential Backup. As time progresses, each Differential Backup will become progressively larger, because each will contain more changes made since the Full Backup was done.

Compared to Incremental back up, Differential back up can cost more time and disk space.

Differential Backup

Differences between Full, Differential and Incremental Backup

Compare full, differential and incremental backup, the differences mainly lie on backup source, backup time, image storage, restore files number and restore speed. Here is a table listing these items.

Backup source

Backup time

Image storage space

Restore files number

Restore speed

Full Backup

All data





Differential Backup

All changed or added data   since last full backup





Incremental Backup

All changed or added data   since last backup (full or incremental)



Two or more


Which to Choose, Full, Differential or Incremental?

Full Backup + Incremental or Differential

With the demonstrations above, you might have found out that the method of "Full Backup + Incremental Backup" or "Full Backup + Differential Backup" will be more convenient than single full backup. Therefore, after a full backup, you can choose whether incremental or differential backup to only deal with the changed and newly added data and files. It will be more efficient.

What's more, the way of "Full Backup +Incremental Backup" has been employed more frequently than other approaches. It will only deal with the changed files since the last backup. Therefore, if you need to back up data regularly, this way will be more appreciated and time saving. The way of "Full Backup + Differential Backup" is also a good solution. However, compared to incremental backup, it will cost more time and also it needs more space to store the image file.