512 MB Memory Stick Pro is only 468 MB?!

[UrbanPhotos]

I just got a Sandisk 512 MB Memory Stick Pro for a Christmas present. I'm happy to have it, but I'm shocked to find that the capacity is only 468 MB! I knew that hard drives and flash media are usually smaller than their advertised capacity, but 44 MB less? That's significant. That's 20 maximum-quality pictures less. I know some of the space is lost to formatting, but the total used space is only slightly more than the total size of the pictures on the stick.

[zinzimaster]

I think that the trick is the difference between Mb (MegoBytes) and Mo (MegaOctets), with the conversion 1000 Mo = 1024 Mb or 1024 Mo = 1000 Mb (I can never remember )

[Boundless]

> ... Sandisk 512 MB Memory Stick Pro ...
> ... capacity is only 468 MB!

Some applications report decimal
MB=1,000,000 bytes
Some report "binary"
MB=1,048,576 bytes

If the actual raw capacity of the MSp is
512,000,000 bytes,
an app reporting "binary" MB will show
488 MB

Storage vendors tend to report decimal MB,
because it inflates the number. What apps
report is so inconsistent as to be useless,
unless they report raw byte counts.

And if what you are looking at is space
available in the file system, there's also
some loss for FAT32 filesystem overhead,
and possibly some space for one or more
index files created by the camera.

[zinzimaster]

I had the idea but you have the math explanation .
good job, i´ll try to remember the count this time :idea:

[UrbanPhotos]

Originally Posted by Boundless

Some applications report decimal
MB=1,000,000 bytes
Some report "binary"
MB=1,048,576 bytes

If the actual raw capacity of the MSp is
512,000,000 bytes,
an app reporting "binary" MB will show
488 MB

True. Even so, the stick only has 490,930,000 bytes of capacity, which is less than 512 MB regardless of how you define a megabyte.

[Boundless]

> Even so, the stick only has 490,930,000 bytes of
> capacity, which is less than 512 MB regardless of
> how you define a megabyte.

Yep. Reports of 488 to 490 MB seem to be common
for "512" flash memories.

SanDisk openly admits that they use decimal MB:
http://www.sandisk.com/tech/faq/30.html

Other subtractions in the shortage are:
- filesystem overhead
- CHS truncation
- mapped-out bad sectors

This sort of false advertising is not likely to change
until lots of people return sticks, or until some
Attorney General upgrades their digicam.

[UrbanPhotos]

The instruction manual for the F717 lists the approximate number of images that can fit on various sizes of memory sticks, and it lists 188 full-size images for a 512 MS Pro. When I put in the blank stick, it says there are 194 left, so the stick apparently doesn't have any less capacity than Sony expects. The 194 is a conservative estimate, too: it assumes the pictures will average 2.4 megabytes each, but I've never actually seen one that large. Since jpgs vary in size, a memory stick almost always ends up holding more than the camera says at first. It makes sense to do it that way. It would be irritating for the stick to end up holding fewer images than expected.