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I burned 24 MB (4 files) to DVD+R but on disk properties in Windows it shows up 28 MB of used space. Why is so large difference? There are no hidden files. I used Windows 7 burning system in Explorer (Mastered Format) with Verbatim disk.

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Have you check the bit size and/or hash of the files on your disc and compared them to the size (NOT size on disk) of your original files to verify they are the exact same size? – ubiquibacon Jan 21 '11 at 19:19
Yes, files on DVD have exact same size and content as originals. – Charles Jan 21 '11 at 19:22
If there are a bunch of small files, sector size might be the reason. DVDs use 2048 byte sectors and most OSs use something smaller (512 bytes for NTFS, for example), so a file that runs into a sector (but is less than 512 bytes) would take 2k on the CD and only 0.5k on your hard drive. – Michael Todd Jan 21 '11 at 19:38
I am not sure so I am not posting this as an answer: Could the Lead-In and the Lead-Out eat 4 MB? I mean for each writing it creates a new session on the disc. – sinni800 Jan 21 '11 at 22:39
Nah, don't sweat it. I don't want to sound jealous or anything :). – sinni800 Jan 24 '11 at 22:38

As @sinni800 pointed out above in the comments, this is your Lead-In and Lead-Out data (and table of contents, possibly) using up that additional space.

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You could've just told me I had the right answer. I'd have posted it ;) – sinni800 Jan 22 '11 at 13:25

Internal fragmentation says:

Internal fragmentation occurs when storage is allocated without intention to use it. This space is wasted. While this seems foolish, it is often accepted in return for increased efficiency or simplicity.

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How would that happen in something freshly written? – tobylane Jan 21 '11 at 21:39
Please explain better. Providing a link isn't sufficient, summarize what's there. – KronoS Jan 21 '11 at 22:24
After inserting disk Windows 7 displayed standard dialog for new disk (question about disk label and format). All was freshly written only once in one session to a brand new disk. I have no third party buring software or non-system burning drivers. – Charles Jan 22 '11 at 0:58
I've voted this answer down because it does not address the problem, and is not summarised sufficiently. – user3463 Jan 22 '11 at 1:30

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