Create a "free space" partition on Mac OSX 

This video helped me so much. I basically used this to resize my volume of the mac boot, so then with mini tool wizard i was able to create unallocated space to give more space to my ntfs windows boot. I would have never managed that without this video. A million Thanks!

Thank you so much. Absolute life saver if you want to install Boot Camp on an older Mac but running Sierra. It doesn't work due to an EFI / MBR Hybrid issue. My Mac Pro late 2013 had no issue installing Boot Camp but a mid 2012 Mac mini (upgraded with an SSD) could not and reported an EFI / MBR issue. I am not alone. The internet is full folks with same problem and equally full of 'how to fix this issue' and most are complex and don't work. For anyone wanting to know, the solution is so simple as to be laughable. This method of creating free space solved it. Note: High Sierra and APFS might work with the following that is my next test but this is all about Sierra and HFS+ and a Windows 10 iso image on the desk top and don't forget you need an attached USB3 SSD for thePC installation and drivers Apple download for you. First follow the usual Boot Camp installation requirements with the attached USB drive for the PC instal and Bootcamp drivers. Note after completion my Mac mini hung on reboot, this part of the problem, the EFI is messed up. So shut down and restart hold option and restart in Mac OS. Run Boot Camp utility app again and select the remove the Bootcamp partition (last option and usually only one available at this point). This removes the partition and restores all the space back to Mac OS. Note: You still have the USB with the PC installation and Bootcamp drivers. Now with your Mac's full space restored by Boot Camp utility use Rui's instructions to create free space, at least 40 GB, I'd suggest more preferably. Now reboot , hold option and select the external USB PC installation .... now Windows installation works! Note: No need to format the space as Fat32 or NTFC. No need to create an EFI or main partition. Do nothing, ... it's all done automatically. Don't over think this if you are techy! ;) With Mac shut down you can now remove the external USB PC install drive. Once done reboot holding option select the EFI partition. Now you are in the Window installation process of several restarts, remember to hold option on restart or often times you are back in Mac OS. One last thing. This installation wasn't done via Boot Camp Utility so none of the Apple drivers for Windows were added. On the PC installation USB you can find them and install from within Windows. They are located in the WindowsSupport folder on the external USB you used. You will eventually get to Windows and Cornata ... :)

This was great, thank you. The revised disk utility is so terrible!

(Running OS Sierra) Is there another way to recover a free space partition and add it back into the Macintosh HD partition? The method used in this video (diskutil resizevolume disk1s2 0g) doesn't work for me. I'm assuming this is just because I am using a later version of OSX. Is there any other way?

how to delete free space partition ??!pls

let's say for instance we reduce the mac disk to from 999 gigs to 900 gigs. then there is 99 gigs of "unallocated space?"

This is not possible anymore T_T

"JIG-abite'????????

For those who cant after MAC OS Sierra, here is the way to do it, With different commands. superuser.com/questions/1270251/resizing-windows-10-bootcamp-partition-manually

how in macos sierra?