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!
You're going to run into issues eventually with an HDD formatted as exFAT due to licensing. exFAT is not free, unlike NTFS or FAT32, and in order for it to be supported by an OS or firmware, it must be licensed from Microsoft, resulting in several OSes and firmware simply not supporting it. NTFS is supported across Linux and BSD (incl Apple's OS, which is built upon BSD). – JW0914 – 2019-08-19T11:48:36.573
6Even with a utility you are still taking a gamble with your data. I can't stress enough that you should back up before migrating file systems. I have only attempted this once and it did not go well. – Supercereal – 2011-02-02T19:11:07.497
@Kyle what can I say, risk is my middle name :) – None – 2011-02-02T19:15:05.123
@Can lol :D good luck! – Supercereal – 2011-02-02T19:19:02.230
NTFS > FAT32 >exFAT – Moab – 2011-02-02T20:15:28.807
1@Moab - is that even possible? Also, if he's got >4GB files it won't work. – None – 2011-02-03T00:31:10.253
@ Randolf, I have never done it, but I could find nothing on going from NTFS directly to exFAT, but did for doing it in 2 steps. Yes 4gb files would need to be moved elsewhere. – Moab – 2011-02-03T00:57:43.347
@Moab, FAT32>exFAT?
@Can, if you have another storage device, you could transfer your files to that, format the drive, then transfer them back (depending on how much free space you have available, how much data is on the drive in question, and how much time you are willing to spend on it). – Synetech – 2011-02-03T00:57:57.040
@Moab - I saw the two-step process too, but I think it's much wiser for @Can to stay on NTFS and leave well-enough alone :-). P.S. I updated my answer to include it, with the proviso of the 4GB limit. – None – 2011-02-03T01:13:06.563
Acronis DiskDirector allows for filesystem conversion without losing data. – None – 2011-12-01T14:44:49.583