What is the recommended boot partition size for Windows 7?

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...

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.

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

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.