How much disk space should I devote to my Linux / partition?

"I think 10 GB is plenty.

I am running a Ubuntu server within 10GB (including /home) and it is puffing along fine. Excluding my files, the system takes up less than 4GB. If you ever find yourself pressed for space, you can always resize the partitions at a later date."

"It highly depends upon the Linux distribution you are going to install,

Because DSL(Damn Small Linux) or Puppy Linux are mere 60 -70 'MB' whereas Fedora goes in 4-5 GB and Ubuntu in 2-3 GB

It even depends upon how much you are going to use Linux, i.e the softwares you are going to install

For Latest Fedora releases 10 GB is enough.

For ubuntu use 5 GB"

For a standard desktop or laptop installation, there is little advantage in separating your partitions. If you know how to use LVM, that's the best solution, but there's nothing wrong with just having one big partition (and a second one for swap).
For a standard desktop or laptop installation, there is little advantage in separating your partitions. If you know how to use LVM, that's the best solution, but there's nothing wrong with just having one big partition (and a second one for swap).

"Swap will be 2x RAM;

This is actually a very old sizing rule and I think it's obsolete. On modern systems (i.e. with 1GB or more of RAM), I give 1x RAM for Swap.

boot will be ~200M.

Wow! How much kernels do you plan to use, 20? For most users, 50Mo is enough.

How much should the OS
receive? I was thinking of giving it
between 15 and 20G (and all else to
/home where most of my files will be
located), but I wasn't sure if it
would need more.

Is there a standard way of determining
the partition size for '/'?

I don't know a ""standard"" way as it highly depends on how much software you'll install and
what you'll be doing with your computer. A server install (mail, database...) will typically use a pretty big separated /var partition. For a personal machine, this is most of time useless. In fact, 10 GB for / should be more than enough for most users. If you plan to install many (and I really mean many) packages, you might need some additional GB, but not more than 15 GB. If you plan to install external softwares (e.g. in /opt), take it into account (I personally have many Java stuff installed in /opt, like commercial app servers that are not really lightweight). If you are going to rip DVDs, add a few more gigs. And indeed, use the rest of the space for /home.

Actually, you should now understand why it's hard to give an absolute answer and experience (i.e. trial error) is the best way to find the ""perfect"" sizing for your machine. But even for an experienced user, needs might change with time. That's why, as someone pointed out, LVM and resizable filesystems are weapons of choice to avoid any pitfalls."