SD Card has wrong capacity

[AndyM]

After flashing an OS to my 16GB micro SD I find that it erroneously reports in, for example, parted as 4GB.

Code:

$ lsblk
NAME  MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda      8:0    0 465.8G  0 disk
├─sda1  8:1    0    2M  0 part
├─sda2  8:2    0  39.1G  0 part /
├─sda3  8:3    0  7.8G  0 part [SWAP]
└─sda4  8:4    0 418.9G  0 part /home
sdb      8:16  1    15G  0 disk
└─sdb1  8:17  1    15G  0 part

Code:

$ sudo parted /dev/sdb
GNU Parted 3.6
Using /dev/sdb
[menu]
(parted) print all                                                       
Model:  (file)
Disk /dev/sdb: 4092MB

I have googled endlessly but cannot find a way of fixing this.
I would like to use the 16GB SD card for data.

Any help would be appreciated as usual.