Confused about "bdf" command?

[Worapoj P.]

Dear all expertise,

I have confused about out put of "bdf" command, please see below

#bdf
Filesystem kbytes used avail %used Mounted on
/dev/vg00/lvol3 3145728 2370414 726944 77% /

If calculate by manual
%used = 3145728/2370414 * 100
= 75.35
~ 76%

Why "bdf" command say 77% ??? but exactly ~76%

Thanks advance for you replies
Worapoj P.

[Alex Glennie · Accepted solution]

Remember the O/S reserves minfree space on the
filesystem (which is not represented in the "used" column of bdf).
minfree defaults to 10% of overall filesystem size and could be 1 possible cause I guess, what type of filesytem .... JFS , HFS ?

[Worapoj P.]

Dear Alex,
Please explain me in both of them(JFS and HFS)

Best Regards,
Worapoj P.