What is Compact OS in Windows 10 and How To Enable It to Save Disk Space


Windows 10 includes tools that helps you use less disk space by compressing the files for the entire operating system. In a nutshell, Compact OS lets you run the operating system from compressed files on both UEFI-based and BIOS-based devices. It’s the driving force that makes Windows devices light-weighted and highly mobile but still have the full capabilities of Windows OS when needed.

What’s involved and how much spaces can be saved?

To make this happen, Windows 10 employs 2 separate and independent approaches, 1) an efficient compression algorithm to compress system files, and 2) recovery enhancements with no requirement for a separate recovery image.

So how much storage space will be saved if a device runs on Windows 10 in a compact OS mode?

With the new efficient algorithm in place, it gives back about 1.5 GB of storage for a 32-bit system and 2.6 GB on a 64-bit. Phones will also be able to use this same efficient compression algorithm and likewise have capacity savings with Windows 10.

The redesigned zero-recovery-image Refresh and Reset functionalities also reduces Windows storage footprint ranging from 4 GB to 12 GB, depending on the make and model of the machine.

When to use?

Running an entire system off a compacted file system sounds great but does affect system’s performance. So to make sure it makes the least impact to the system, Windows considers a number of factors when assessing whether a device should use compression or not.

It’s all automatic. Normally you don’t need to worry about this too much unless you are at a point where your storage is running really low.

So, how to tell if my system is running in Compact OS mode?

Open Command Prompt window, and type the following command.

Compact /CompactOS:Query

If it is running in the Compact OS mode, you will see something like this:

Command Prompt - Compact

If not, it will tell you that it’s because Windows has determined that it’s not beneficial for this system.

How to turn it on or off

Assuming you realize the fact that by turning on Compact OS on a system Windows determines not beneficial you are trading off some of your horse power for getting more storage space back.

And if you are ok with that, open Command Prompt as Administrator or Windows PowerShell (Admin) and type the following command.

Compact /CompactOS:Always

PowerShell - CompactOS Always

To turn it off to get a performance boost, use

Compact /CompactOS:never


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