This question already has an answer here:
I'm new to Raspberry Pi.
The 8 GB SD card that came with my RPi 3 type B showed only 500 MB free, probably due to the pre-installed Mathematica (thanks WRI!).
So I moved the card image to a 32 GB SD card using Win32 Disk Imager. I decided to use
fdisk to expand the root partition to the card's extents:
$ sudo fdisk /dev/mmcblk0
where I removed the root partition, re-created it with the same start sector, but using the default end sector, which is the last sector on the card. Concluded with
w to save everything. When after rebooting I went to
fdisk again it now shows a 29.7 GB partition, which seems correct, but File Manager PCManFM reports:
Free space: 541 MiB (Total: 7.2 GiB)
Did I miss anything? How can I fix the numbers File Manager is reporting (assuming they are wrong)?