SanDisk Ultra USB 3.0: Only 114 GB of 119 GB available?

Hey everyone,

I just bought a 128 GB USB flash drive. I know that due to the 1024-bytes convention it doesn’t show 128 GB in Windows. However, I do understand that 128 GB means 128,000,000,000 bytes. That is even written in the fine print on the backside of the blister pack. And 128,000,000,000 bytes translates for me (/1024^3) to 119 GB. Now, my stick only shows 114 GB (or 123,000,000,000 bytes). So there are definitely 5 GB missing from what is advertized!

So, where did this space go? Does SanDisk use 5 GB for firmware and wear leveling? Why do other manufacturers (e.g. Lexar) deliver what is advertized (i.e. 128 GB appear with 119 GB in Windows)?

Thanks for answering,


this the explination on the sandisk knowledebase. i underlined the specific explination for the capacity difference. This is common among all flash memory manufacturers. 

Why is the capacity of my device (as reported by many operating systems) different than the capacity that is listed on its label?

All SanDisk products include the total capacity, at an unformatted level, that is stated on the product packaging. For example, a 128GB SanDisk USB flash drive has a total capacity of 128,000,000,000 bytes at the unformatted level (where 1GB=1,000,000,000 bytes).

Definitions of a Megabyte :
1. Operating Systems commonly define capacity as follows:
     - Kilobyte (KB) as: 2 to the 10th power (1,024 bytes)
     - Megabyte (MB) as:  2 to the 20th power (1,024 X 1,024 bytes = 1,048,576 bytes)
     - Gigabyte (GB) as: 2 to the 30th power (1,024 X 1,024 X 1,024 bytes = 1,073,741,824 bytes)

2. Disk Drive and Flash Memory Card Manufacturers commonly define a MB as one million bytes (exactly 1,000,000 bytes) and a GB as one billion bytes (exactly 1,000,000,000 bytes). 

SanDisk defines 1 GB as 1,000,000,000 bytes.  Operating Systems define 1 GB as 1,073,741,824 BYTES.

Note: Some capacity is used for formatting and other functions and thus not available for data storage.

A portion of the total capacity is used to store certain functions including optimizations of the memory that support performance and endurance and therefore is not available for user storage. This is disclosed on our packaging and marketing materials when you see the statement “Actual user storage less.”

As a leader in flash storage technology, SanDisk offers multiple products at different speeds and capacities to address a variety of consumer needs. To provide the optimum product for you, we’re continuously improving and updating our technology, products, firmware, and design. Continual improvements and updates are made to our product (both new products and existing product lines) and can include changes to the basic file structure, formatting and other functions. These optimizations may result in variances as to the amount of memory space that is available for user storage, but are essential to performance and endurance of the products.

Maybe this helps:

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This is really annoying. Did you actually READ what I wrote?

I am well aware of the difference between actual size and what my operating system (i.e. Windows) shows as available capacity. According to this, a 128 GB stick should show up as 119 GB. However, the stick that I bought only shows 114. Yes, 114 GB unformatted. So the 5 GB is not lost due to formatting (and formatting only takes a couple 100 MB at max). So it is still 5 GB less than advertized! How do you explain this? 5 GB for system functions or performance? Really? If that is the case, then I call this false advertizement! If the stick needs 5 GB for those functions, SanDisk should add 5 GB more, so that available capacity becomes indeed the advertized 128 GB!

Oh: I received a replacement from Amazon now, because I claimed warranty. The new one has 1 GB more than the first one, but still only 115 instead of the advertized 119 GB. :confounded:

See the underlined number in the attached screenshot. According to the packaging (with the 1 GB = 1,000,000,000 bytes) this number should read AT LEAST 128,000,000,000.


The replacement has 1 GB more!!  Sounds like your source is selling counterfeits.  Or used drives.  Return it and find a different source.

Well, my source is Amazon. And no, not marketplace. Amazon directly. And they were still in the original blister packaging (that you cannot reseal). But comments on the product suggest I’m not the only one with this inconsistency.

I have a 31.9 GB capacity iXpand to bring with me on a lengthy trip, along with another flash drive. Debating about whether or not to bring my 1TB external harddrive along as well, I decided to experiment with how much storing I could get away with by seeing if I could copy the 22 or so GB LOTRO game launcher onto the iXpand.

The iXpand got hot to the touch and had only about 8 GB remaining by the time the game launcher was completely copied onto it. I decided it wasn’t worth taking up so much space on that drive, and deleted it from the iXpand.

But iXpand still gets hot to the touch after being plugged in and still only shows 8 GB available.

Is this reparable?

Check response here: