How is the size of an LVM volume calculated?

Today I'm configuring kickstart, and when I tried to set the LVM sizes, Anacond protests that there is no free space to create LVM with VG size. Well I could figure out that --grow option can continue the installation w/out prompt to solve this problem, but I need to know how I can calculate the correct VG size to group my LVMs? I just could see something related in AIX system but I thing that is not about my question, and no that isn't a bug. Error: **storage configuration failed: ('new lv is too large to fit in free space', 'vg00')** The wrong configuration: part /boot --fstype="xfs" --ondisk=vda --size=500 part pv.01 --fstype="lvmpv" --ondisk=vda --size=9500 --grow volgroup vg00 --pesize=4096 pv.01 logvol / --fstype="xfs" --size=9000 --name=root --vgname=vg00 logvol swap --fstype="swap" --size=250 --name=swap --vgname=vg00 logvol /home --fstype="xfs" --size=250 --name=home --vgname=vg00 The correct configuration: part /boot --fstype="xfs" --ondisk=vda --size=500 part pv.100 --fstype="lvmpv" --ondisk=vda --size=9739 volgroup vg00 --pesize=4096 pv.100 logvol swap --fstype="swap" --size=250 --name=swap --vgname=vg00 logvol /home --fstype="xfs" --size=250 --name=home --vgname=vg00 logvol / --fstype="xfs" --size=9000 --name=root --vgname=vg00 When I used the --grow option in partition, the kickstart create a anaconda-ks.cfg with that configuration above, I just can't understand how the size=14079 is calculated. The original-ks.cfg have the option --grow ;) Could someone give a idea about LVM math? Thx