---
name: "btrfs-space-calculator"
section: "1"
platform: "linux"
package: "python3-btrfs"
version: "15-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/btrfs-space-calculator"
---

# btrfs-space-calculator(1)

calculate usable and wasted space

## NAME

btrfs-space-calculator - calculate usable and wasted space

## SYNOPSIS

**btrfs-space-calculator** \[*args*\] *sizes*

## DESCRIPTION

The btrfs-space-calculator program shows the amount of allocatable space on btrfs physical and virtual level, and the amount of unallocatable space resulting from having differently sized block devices added to the filesystem.

In a btrfs filesystem, raw storage is shared by data of different *types* (System, MetaData and Data) and *profiles* (e.g. single, DUP, RAID1). Also, a filesystem can have multiple block devices of different sizes attached.

An example:

    \-$ btrfs-space-calculator -m raid1 -d raid1 2TB 500G 1TB\
     Target metadata profile: RAID1\
     Target data profile: RAID1\
     Mixed block groups: False\
     Total raw filesystem size: 3.18TiB\
     Device sizes:\
       Device 1: 1.82TiB\
       Device 2: 465.66GiB\
       Device 3: 931.32GiB\
     Metadata to data ratio: 1:200\
     Estimated virtual space to use for metadata: 7.00GiB\
     Estimated virtual space to use for data: 1.36TiB\
     Total unallocatable raw amount: 465.66GiB\
     Unallocatable raw bytes per device:\
       Device 1: 465.66GiB\
       Device 2: 0.00B\
       Device 3: 0.00B

Note that most physical disk vendors specify their sizes in GB or TB, while partitions created in your average partition table or with lvm2 etc... are usually using MiB, GiB and TiB.

## OPTIONS

- **-h**, **--help**

  Show the built-in help message and exit.

- **-m**, **--metadata** *PROFILE*

  Metadata profile, values like for data profile.

- **-d**, **--data** *PROFILE*

  Data profile, raid0, raid1, raid5, raid6, raid10, dup or single.

- **-M**, **--mixed**

  Use mixed block groups (data and metadata profile must match).

- **-r**, **--ratio** *RATIO*

  Data to metadata ratio, e.g. 200 (the default), which means allocate 0.5% for metadata. Setting this ratio only makes sense for non-mixed filesystems. When using this option in combination with -M, it will be ignored.

## SEE ALSO

This program is an example of what can be done using the python-btrfs library.

Source and documentation on github: https://github.com/knorrie/python-btrfs