See System Disk Space Usage

Running out of space on your server? To get an overview of how much space you have on your machine you can use the handy df linux command which reports file system disk space usage.

-h, --human-readable    Print sizes in human readable format, e.g. 1K, 324M

--block-size=           Show the usage in the block size specified, e.g. --block-size=GB

If you want to display the output in megabytes or gigabytes you can do the following

# display in megabytes
df -h --block-size=1MB

# display in gigabytes
df -h --block-size=1GB