40GB

$ df -H
Filesystem     Size    Used   Avail Capacity  Mounted on
/dev/ad0s1a    520M     82M    396M    17%    /
/dev/ad0s1e    1.0G    535k    954M     0%    /tmp
/dev/ad0s1f     25G    8.9G     14G    39%    /usr
/dev/ad0s1d     10G    2.5G    7.0G    27%    /var