Convert NTFS volume to exFAT (without losing contents)
Solution 1:
To answer your question: no, there is no utility.*
I'd stick with NTFS. It's been around longer than exFAT, it is stable, and no one is forcing you to use the features like compression, security and encryption. It's also supported on a lot more platforms than exFAT, including Windows itself (notwithstanding the patches you can install).
exFAT is designed primarily for removable drives like USB thumb drives, so I'd use it for that, but not for a hard drive.
**(As @Moab points out in the comments, there are ways to do this using two separate conversions, from NTFS to FAT32, and then FAT32 to exFAT, but you'd be held ransom to FAT32's limitations during the conversion, which includes a maximum of 4GB on file sizes.)*
Solution 2:
Assuming you are using Microsoft Windows, I have an idea for you. Since I was also looking for this solution and found nothing really working! I did a workaround.
What you can do is, Shrink the partition in your Portable, using Windows management tools (right click "computer" and goto Management, then goto "Disk Management"). To shrink the partition, click a partition that you want to shrink, and click on Shrink. Enter the size that is enough to copy all the data, then continue.
When you are done with creating another partition, move the data to the new partition, which is pretty time consuming I get that. What I did, is left my laptop for hours to get this done! Caution: Portables are not supposed to run for hours. I have reliable Portable so I did it.
Here you have two solutions! One to simply format using the right clicking on partition and click on format which will work on external hard drives only. However, I am also giving following solution for someone who may want to format the internal partition to exFat. Windows do not allow internal partitions to be formatted in ExFat by default so we need to follow Disk Part approach!
Note that, if you want to move large files to Portable or Internal Drive, set the Allocation Size to 4096 Bytes, as in the case of NTFS. When you are handling Diskpart, Unit=4096 is doing the same.
Follow as under:
1: Diskpart
2: List Disk
3: Select Disk x Note: x is the disk number you want to deal with.
4: list partition
5: select partition x Note: x is the partition number you want to format to exFat
6: Format FS=ExFat UNIT=4096 Quick
7: You are done!
Good Luck!
Solution 3:
If you couldn't use of the above normal method, you can use of Parted.Magic tool for that goal. Download it's .iso file (it just need a little googling!) and burn it to a CD/DVD/USB stick then boot your computer from it. Then attach your HDD into computer and double click on partition Editor item (see this) Then you can see this window. Right click on the rectangle which is showing the size of your HDD, then convert it to whatever you like. PS. You should observe the considerations said about loosing data in above answer. Good luck.