The following command displayes in GiB

pvdisplay

To display in GB use the following command:

pvdisplay --units G

lvcreate -L 10G name

Creating a logical volume from a specific volume group

lvcreate -L 1500 -n testlv testvg

You can also use the -l argument of the lvcreate command to specify the percentage of the remaining free space in a volume group as the size of the logical volume

lvcreate -l 100%FREE -n yourlv testvg