# GB Calculation on SSD. Am I just lucky?

I have recently installed a OCZ Vertex Plus R2 VTXPLR2-25SAT2-120GB 2.5 120GB SATA II MLC Internal Solid State Drive (SSD) 120 GB SSD. I figured I would have about 110 to 112 GB knowing that hdd/ssd and other mass storage device manufactures use the 1000x1000x1000 vs OS using the math of 1024x1024x1024 to calc a gig. then take into account the format overhead and so on.

So am I just lucky that my SSD is showing 115 GB? shown as drive J:. is my math wrong in that if I divide 120,000,000,000 by 1024/1024/1024 that it should be 111.76 GB?

I should note that windows 7 is on it and NTFS formatted.

I am not complaining about the "extra gigs" I am just wanting to understand the variance in what I expected to what I got. Any answers?

Edit: I updated the drive info OCZ Vertex Plus R2 VTXPLR2-25SAT2-120GB 2.5" 120GB SATA II MLC Internal Solid State Drive (SSD)

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It is more the case that you got unlucky. OCZ isn't using the SI prefixes for their drives, so a 120GB drive should show up as 120GB in windows (I think it formatted is more like 119.7 or some such). The SandForce drive has a technology called RAISE, which is a bit like RAID5 but across NAND dies. This mean one die worth of storage is lost to parity data. When OCZ then moved from 32nm to 25nm NAND the die size doubled and thus the amount of storage lost to parity data doubled as well. So you are really getting 4GBs less than promised. The loss of dies also means the drive is a bit slower. On the other hand the \$/GB of 25nm NAND is much less than 34nm NAND.

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I updated the drive info as I was a little off and it may be important. The drive uses an Indilinx controler and is OCZ Vertex Plus R2. – Carl B Sep 5 '12 at 13:59
@CarlB - This answer is still valid. – Ramhound Sep 5 '12 at 14:31
Well this has dashed what I thought was good fortune :( – Carl B Sep 6 '12 at 1:28