Disk partitioning unit ?

Hi!

I would like to ask question regarding to the unit for disk partitioning for RHEL 7.1.
I am bit confused with this so I appreciate if someone can help me.

In the installation guide P 162 it says ,
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/pdf/Installation_Guide/Red_Hat_Enterprise_Linux-7-Installation_Guide-en-US.pdf

"Desired Capacity - enter the desired size of the partition. You can use common size units
such as kilobytes, megabytes, gigabytes, or terabytes. Megabytes are the default option if you do
not specify any unit"

In the example screen shot, for /boot partition,
when you actually add the partition, the unit is shown in "MiB" which stands for Mebibyte.

My question is , before starting the installation,
should you design the filesystem sizing in "Megabyte" or "Mebityte"?