Windows 8 Without Optical Drives: How Much Space?

Posted Tuesday January 29, 2013 at 2:52:40 pm in Technology

The internet is abuzz with talk of the 64GB Surface Pro reportedly having only 23GB of free space. But how is this the case?

Starting point: 64GB?

Well, first and foremost: actual capacity never matches the advertisement capacity. Case in point: a 64GB SSD (like in the Surface Pro). Companies define a gigabyte (GB) to be 1,000 megabytes (MB), but in reality this isn't correct.

The breakdown works like this:

  • 1GB = 1,024 MB
  • 1MB = 1,024 KB
  • Etc, etc.

But how much is the actual capacity? It varies and depends on a variety of factors: the filesystem being used, indexing, journaling, etc. It can even vary from a hard disk drive (HDD) to a solid-state disk (SSD).

But what it really comes down to is a difference in number systems. The idea of a giga, mega, kilo, etc. these numbers are all decimal based numbers as defined above (i.e. 1GB = 1,000), when in reality computers rely on a binary system. This essentially means 2 possible values (0 or 1, hence "bi"). In the above speak, we can determine the difference between decimal (see: advertiser speak) and binary (actual) via the following:

  • Advertisement: 1KB = 1,000 bytes
  • Actual: 1KB = 1,024 bytes. Derived via 2^10. 

One of the best ways to sum this up is to actually see what the breakdown is as you go up the ladder. Byte, KiloByte, MegaByte, GigaByte, etc. 

A pretty solid article which breaks it down is located here: Formatted capacity confusion clarified. In particular, this:

Hard disk manufacturers assume: Kilo = 10 3 = 1000 (kB)

File system assumes: Kilo = 2 10 = 1024 (KiB)

Let us calculate kB, MB, and GB to KiB, MiB and GiB factors:

kB - KiB: 1000 / 1024 = 0.977

MB - MiB: (1000 * 1000) / (1024 * 1024) = 0.954

GB - GiB: (1000 * 1000 * 1000) / (1024 * 1024 * 1024) = 0.931

Back to our original 64GB situation we'll use a multiplier of 0.931:

64GB * 0.931 = 59.58GB

As I've said above, the issue comes down to convention. Advertiser speak uses decimal based numbers when speaking of gigabytes, whereas computers really use a binary system. In the situation of a GigaByte (GB), when it comes to computers one should really use a gibibyte (GiB). From Wikipedia:

The gibibyte is a standards-based binary multiple (prefix gibi, symbol Gi) of the byte, a unit of digital information storage. The gibibyte unit symbol is GiB.[1]
1 gibibyte = 230 bytes = 1073741824bytes = 1024 mebibytes


The gibibyte is closely related to the gigabyte, which is defined as 109 bytes = 1000000000bytes, but has been used as a synonym for gibibyte in some contexts (see binary prefix.) In terms of standard gigabytes, 1GiB ? 1.074GB.

Source: Gibibyte

Now that that is out of the way, before the Surface Pro has Windows 8 installed on it, it already has lost about 4.5GB just by nature of "confusion". 

Actual starting point: 59.58GB

So, now we're at 59.58GB. Apparently Microsoft has confirmed with Softpedia that the 64GB Surface Pro will only have 23GB free. So, this really means about 36.58GB is being used for Windows 8 and anything else that comes with the tablet. 

From Microsoft themselves, Windows 8 System Requirements:

Hard disk space: 16 GB (32-bit) or 20 GB (64-bit)

It's important to note that the Surface Pro utilizes the 64 bit version of Windows 8. This knocks off another 20GB.

After Windows 8 installation: 39.58GB

After Windows 8 is installed, we're down to 39.58GB. But Microsoft is saying that only 23GB is free. Where's that other 16.58GB going? Well, it's also reported (and it makes perfect sense) that the Surface Pro (like the Surface RT) will have a recovery partition. Being that Windows 8 is a much larger install than Windows RT, it stands to reason that the recovery partition must be larger.

But why is there a recovery partition? The Surface Pro (and RT) do not have optical drives. With Windows 8, Microsoft has improved the recovery features of Windows to make it easier on the user. Put 2 and 2 together, and you have a situation where Microsoft wants the user to be able to either Restore, Refresh, or Reset your PC.

Since there isn't an optical drive, there isn't a physical media that holds the Windows 8 operating system. So there needs to be somewhere in the Surface Pro for the system to restore itself. That place is  the recovery partition. Could the recovery partition be 16.58GB? It's possible. But it's also possible that a portion of that 16.58GB is reserved for Microsoft applications that are installed by default on the Surface Pro. To this date we don't know what comes out of the box with the Surface Pro application wise. What we do know is that Office is not included (the Surface RT comes with Office). But it's probably safe to safe that the large majority of that remaining 16.58GB is reserved for the recovery partition.

Freeing up space

The Pro has a USB 3.0 port, and Microsoft says that the recovery partition can be backed up to a backup bootable USB drive. This should recover a good portion of that 16.58GB that was left. And if we assume that most (all) of that is reserved for the recovery partition, then we should really have nearly 40GB free for our use (if the recovery partition is backed up to an external piece of physical media).

Of course there are additional options when it comes to adding "capacity" to the Surface Pro:

  • SkyDrive (7GB free)
  • MicroSDXC slot (standard supports up to 2TB, but 64GB cards are only $50)
  • Hooking up an external hard drive, jump drive, etc. via the USB port.

Either way, I hope this demystifies the 64GB to 23GB jump...and also gives you options to boost that 23GB to 40GB and beyond. 

The opinions expressed herein are my own personal opinions and do not represent my employer’s view