user6009: I want to make portable client so I found with start bitcoin-qt.exe -datadir=data
But where is default data dir so I can move it there?

user9301: It depends on your operating system.  Read about it here.
Linux
~/.bitcoin/

Mac
~/Library/Application Support/Bitcoin/

Windows
C:\Documents and Settings\YourUserName\Application data\Bitcoin (XP)

C:\Users\YourUserName\Appdata\Roaming\Bitcoin (Vista and 7)


6009: <p>I want to make portable client so I found with <code>start bitcoin-qt.exe -datadir=data</code></p>

<p>But where is default data dir so I can move it there?</p>
 9301: <p>It depends on your operating system.  Read about it <a href="https://en.bitcoin.it/wiki/Data_directory" rel="nofollow"><strong>here</strong></a>.</p>

<p><strong>Linux</strong></p>

<pre><code>~/.bitcoin/
</code></pre>

<p><strong>Mac</strong></p>

<pre><code>~/Library/Application Support/Bitcoin/
</code></pre>

<p><strong>Windows</strong></p>

<pre><code>C:\Documents and Settings\YourUserName\Application data\Bitcoin (XP)

C:\Users\YourUserName\Appdata\Roaming\Bitcoin (Vista and 7)
</code></pre>
