Is there a way to find out the used size of an umounted filesystem?

I want to resize the ext4 / filesystem, so I boot into a live Lubuntu using a Lubuntu bootable flash drive. Since the / filesystem is not mounted, I don't know how much I can shrink it.


  • 1
    I would use gparted, it is a graphical tool. I love command live, but I do this so infrequently. Graphical tools are good for infrequent jobs, and visualisation. Both of which apply here. Feb 23, 2019 at 18:50

1 Answer 1


For ext2/3/4 filesystems you could use dumpe2fs or tune2fs -l (from e2fsprogs) to get the total, used, and available block counts (among other properties) e.g.

$ sudo tune2fs -l /dev/sda5 | grep -i block
Block count:              3999755
Reserved block count:     199987
Free blocks:              3396721
First block:              0
Block size:               4096
Reserved GDT blocks:      1024
Blocks per group:         32768
Inode blocks per group:   509
Flex block group size:    16
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
Journal backup:           inode blocks
  • Thanks. Can you make the output in human readable sizes (e.g. GB/MB)
    – Tim
    Feb 23, 2019 at 18:50
  • For example <<<'scale=1;(3396721)*4096/2^30' bc to get it in GiB, and <<<'scale=1;(3396721-199987)*4096/2^30' bc to make it match approximately the output of df -h (df works only when mounted of course).
    – sudodus
    Feb 23, 2019 at 21:44

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