Disk Size of files on HPS+ vs Fat32

Hi,

The other day my mum gave me her external hard drive (WD, 750GB) to put on some videos and TV shows for her. When I plugged the external HD into my Macbook I found that I couldn't write to it because it was formatted as NTFS.
So, knowing my mum also uses a macbook and would probably like to write to the External HD in the future, I decided that I would re-format it to FAT32 for her.

The external HD had a lot of photos on it and a few home videos, and these are important to my mum so I wanted to make sure I didnt permanently delete any of them. I copied the whole contents of the external HD onto my macbook using the 'Duplicate' function. Approx 37.5 GB was copied into a folder on my desktop (i know...a lot of photos, just shy of 12,000 items in total).

I then reformatted it with disk utility into FAT32. Now I can write files to it using my macbook.

So now i transfer the photos back from my desktop back to the external HD.
To make sure I got all of them I had a look at the size of the disk and made sure they matched up.

Strangely, in Finder-->Get Info, it shows that the total used disk space is 32.5 GB for the photos from the desktop, but only 27.8 GB for the photos on the reformatted external HD. I've looked through every subfolder of all the photos and as far as I can tell, every photo/video file has been moved across.

So my question is: Is there a difference in file sizes for Fat32 and HFS+ ??
e.g. could 37.5GB on HFS+ translate to only 27.8GB on FAT32? (keeping in mind we're talking nearly 12,000 individual items.)

...or have I accidentally lost about 10GB of her photos?

Formatting the external hard drive to FAT-32 may not have been a good idea as FAT-32 not only wastes cluster space, it's also limited to a maximum file size of around 4 GB. Which means any movies or videos larger than 4 GB can not be stored on the drive. You probably should have formatted that drive to HFS+.

There will be a difference in space used, however, I'm not sure it should have been 10 GB. Don't erase the originals from your internal hard drive until you can verify that all the photos and videos have been transferred correctly. Were there by chance any videos that were larger than 4 GB?

Thanks for your reply. I did consider formatting to HFS+ however she does still use another windows computer at home as well as her macbook air. FAT32 seemed to best option for compatibility between both machines.

There aren't any files larger than 4GB...the largest I can find is 788MB so i don't think that theres any >4GB files that weren't re-transferred back to the external HD. I'm going to keep everything on my internalHD for now just in case.

The only thing I could think of is if theres hidden files that werent transferred across from the internal HD to the external HD....