I started using one big partition for everything and separating data out with folders when I got my current computer years ago. I'm preparing to upgrade my system from Windows XP to Windows 7, and I thought I might go back to putting my data on a separate partition.

Most likely I'll just use the default OS install. My current Program Files tree has ~16 GB of stuff.

Thinking ahead though, I've had Windows XP installed for years. Who knows what applications I'm going to install down the line?

This, of course, begs the question: How big do I make my Windows 7 install partition?

  • 4
    I knew the answer would be "it depends on what you do" but the one I accepted feels the most correct based on the other ranges of 30-55 GB for comfort. Ideally I don't want to wipe and re-install for years to come.
    – dwj
    Oct 22, 2009 at 16:25

13 Answers 13


I've done half a dozen Windows 7 installs this week and the "base" install takes nearly 20 GB in my experience. I'm writing post this on my new Windows 7 Ultimate rig. I've installed literally nothing but drivers and 20 GB is used up already on my OS partition.

This is also confirmed by the Windows 7 System Requirements, which also lists that you need 20 GB at least to run Windows 7. So, I would recommend you to use at least 60 GB and to install your applications in a separate data partition.

Note that your system partition tends to grow over time due to updates, temporary files, logs and that kind of things; so, to anticipate this you would need sufficient space. If you look at other answers, you will see that some people have 40 or 50 GB so choosing 60 GB makes sure that you don't hit the border yet.

Given the hard disk sizes nowadays, 10 - 20 GB more shouldn't hurt. Unless you run a SSD...

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    What is the reason for installing into the separate data partition? I do want a separate data part., but why go through the hassle of putting the apps there?
    – Posipiet
    Dec 13, 2010 at 16:01
  • @Posipiet: It's not really a hassle, just junction point Program Files. Oct 12, 2011 at 21:30
  • I had 40GB and installed all programs where possible to another partition + moved my user folder to the other partition. Unfortunately many programs (like Google Chrome) install themselves automatically on the system partition. After 10 months of updating windows I hit the 1GB-free-border. Growing the first partition is no fun, as all data on the second partition has to be moved forward by the grow amount (especially bad for SSDs I guess). So I consider 60GB the minimum Win7 system partition size.
    – fabb
    Sep 4, 2013 at 18:00

I gave Windows 7 a 100 GB partition on a 1 TB drive, and according to the Windows Experience Index (WEI) I got a 7.2 for the drive. It's substantially better than using the whole 1 TB, which was more in the 5.9-6.0 range.

I read it has to do with the efficiency of having the OS partition first (outer-most part of the platters on the HDD), and that a smaller partition is more efficient. Believe me, there was a discernable improvement.

  • +1. This is actually called short-stroking and is commonly used in datacenters to enhance hard disk performance at the cost of capacity.
    – bwDraco
    Oct 1, 2015 at 23:28

Primary partition is created on the outer track of the hard drive waffle, which makes the overall data read/write much faster then un-partitioned drive (google it). Its not about just "flexibility" or "content management", its about how fast you want your OS or Apps to load, haedrive read/write is a big bottle neck on an un-partitioned drives, and its not a marginal gain in performance, it will make the drive 3-4 times faster depending up on how small you make the partition.

ps. if you don’t know the answer don’t post garbage information like "The reasons for multiple partitions are not good enough to overcome the hassle" is misleading and absolutely not true


In a related question, Windows 7's base install was reported as weighing in at about 6 GB, compared to about 1.5 GB for a Windows XP install.

I've gotten by pretty well with a 20 GB partition for Windows XP, but I've been installing the big applications (games) to a separate drive. I estimate 40 GB should be all you'd need for a Windows 7 system partition.


The minimum requireed partition size for Windows 7 is about 9 GB. That said, most people that I've seen recommend at MINIMUM 16 GB, and 30 GB for comfort.

Naturally, you'll have to install programs to your data partition if you go too small, but that's up to you.


It changes due to your needs. For example, if you are a mid-level computer user you need 50 GB. But if you like to install tons of applications you can have 100 GB. Also, it's up to your needs and your total space. For example, I got a hard disk drive of 120 GB and using 55 GB for Windows Vista Home Premium.


Well, it IS true that separate partition for the OS equals better performance. If you could have a separate HDD physically it'd be even better, but there'a also a balance to be maintained - balance of size. Too big and your HDD's read-writes will slow down the PC performance. Too small and your OS will eat the space too quickly.

I personally have Windows 7 Ultimate installed on a separate partition which is 35 GB and it worked well for me for almost two years now, but it starts to overgrow this amount of space... There is only 2.37 GB of free space left and my Windows directory weights 22.2 GB now (and growing) so while the recommendation of 60 GB is a bit excessive, I'd recommend 40-50 GB. Although you could buy a cheap 80 GB HDD and dedicate it only for the OS...


Having been in this same predicament recently, I can say that the advice on here already is about right. It's amazing that you can have a fully loaded Windows XP PC on a handful of GB, but Windows 7 not so. I really wouldn't recommend a minimum of less than 50 GB, 60 GB would be better as you'll have some extra room for the future. Less than that, you'll notice a pinch not long after your new install.


I have a 36 GB partition and my Program files folder is 4 GB. Currently I have 12 GB free. Doing the math you should have a partition around 50 GB if you want don't want a crowded system partition.


Make one big drive. It's easier. All kinds of programs store things on the system drive.

The reasons for multiple partitions are not good enough to overcome the hassle.


Buy a 64 GB SSD disk for the OS and 1 TB for data and games. After three years, migrate 64 GB to 128 GB and 1 TB to 4, respectively.

  • Tom Wijsman: the changes in my post you did, make no sense at all
    – jet
    Oct 13, 2011 at 11:15

I also did a clean install, and after removing my "windows.old", I got the install down to around 17 GB. I'm setting up a dual boot Windows 7, Ubuntu NBR, and a separate data partition. Giving Windows 7 about 40 GB, Ubuntu gets 20 GB and the remainder as a FAT data partition for shared data.

  • Ubuntu 20GiB? What are you planning? ;) The pure system partition (if /home is on an extra partition) needs 7GiB top.
    – Bobby
    Aug 11, 2010 at 8:54

I have a netbook which can only have one drive. In my experience, 50 GB isn't enough if you plan to load large applications like games on the system drive. I recommend 50 GB if you don't have any games, or 100 GB with games.

Don't forget that iTunes will store backups several GB in size on the system partition. If you use that application you also need to up the space from 50 GB.

  • 1
    Starting from Vista you can redirect directories to your other partitions by using NTFS symbolic links. You can do it in vista too with Sysinternals' utility called junction.exe.
    – Henno
    Sep 8, 2011 at 18:13
  • Typo: I meant in XP, too.
    – Henno
    Sep 8, 2011 at 18:27

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