When running the standard fdisk -l command, partition sizes are displayed in sectors by default. For example:

Disk /dev/sda: 238.5 GiB, 256060514304 bytes, 500118192 sectors
Device       Start       End   Sectors  Size Type
/dev/sda1     2048   1050623   1048576  512M EFI System
/dev/sda2  1050624 500117503 499066880  238G Linux filesystem

To make fdisk show sizes in more readable units (MB/GB), you have several approaches:

1. Using the -B flag

The most straightforward method is to use the -B (block size) option:

fdisk -l -B=1M  # Shows sizes in megabytes
fdisk -l -B=1G  # Shows sizes in gigabytes

2. Alternative with blockdev

For more consistent output formatting, combine with blockdev:

blockdev --getsz /dev/sda | awk '{print $1/2048}'  # Size in MB
blockdev --getsz /dev/sda | awk '{print $1/2097152}'  # Size in GB

3. Parsing fdisk Output

For scripting purposes, you can parse the default output:

fdisk -l /dev/sda | awk '/^\/dev/ {print $1,$2/2048"MB"}'  # Convert sectors to MB

Here are some common use cases with human-readable output:

# List all partitions with sizes in GB
fdisk -l -B=1G

# Show specific disk info in MB
fdisk -l /dev/nvme0n1 -B=1M

# Script to show all disks with GB sizes
for disk in $(lsblk -d -o NAME -n); do 
  echo "===== $disk ====="
  fdisk -l /dev/$disk -B=1G
done

• The -B option requires fdisk from util-linux 2.23 or later
• Older systems might need to use alternative methods
• For scripting, always verify the fdisk version first

When working with disk partitions in Linux, the fdisk -l command is a fundamental tool. By default, it displays partition sizes in sectors, which isn't always the most intuitive format for quick analysis:

Disk /dev/sda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Device     Boot   Start       End   Sectors  Size Id Type
/dev/sda1  *       2048   1050623   1048576  512M 83 Linux
/dev/sda2       1050624  41943039  40892416 19.5G 8e Linux LVM

For better readability, you can use these alternative approaches:

Method 1: Using --bytes, --sectors, or --unit

The modern version of fdisk supports explicit unit specification:

sudo fdisk -l --units=cylinders
sudo fdisk -l --units=sectors
sudo fdisk -l --units=bytes

For megabytes and gigabytes, combine with other tools:

sudo fdisk -l | awk '/^Disk \/dev/ {size=$5/1024/1024; print $1,$2,$3,size"MB"}'

Method 2: Using lsblk for Better Readability

For most use cases, lsblk provides more human-friendly output by default:

lsblk -o NAME,SIZE,FSTYPE,MOUNTPOINT

Example output:

NAME   SIZE FSTYPE MOUNTPOINT
sda    20G        
├─sda1 512M ext4   /boot
└─sda2 19.5G LVM   /

For scripting purposes, you can create a custom parser:

sudo fdisk -l | awk '
BEGIN {
    units["bytes"] = 1;
    units["sectors"] = 512;
    units["kB"] = 1024;
    units["MB"] = 1024*1024;
    units["GB"] = 1024*1024*1024;
}
/^Units:/ {unit_size=$5}
/^\/dev/ {
    size=$5*unit_size/units["MB"];
    printf "%s: %.1fMB\n", $1, size
}'

To make this persistent, add an alias to your ~/.bashrc:

alias fdiskh="fdisk -l | awk '/^Disk \/dev/ {size=\$5/1024/1024; print \$1,\$2,\$3,size\"MB\"}'"