Size of LXC container - ( driver btrfs)

Just want to check, whether the following will give me the size of the each of the container on disk
My driver is btrfs, lxc version: 3.0.3
cd /var/lib/lxd/storage-pools/default/containers
du -ch mycontname1 | grep total ??
du -ch mycontname2 | grep total ??

Regards.