krunchynator
1 Nickel

XPS 15 has only 461GB SSD instead of 512GB

I thought my XPS 15 had 512GB SSD, because it said so everywhere from the product tech spec page to all my order receipts and even the sticker on the box in which it was delivered. But when I open explorer and go to "This PC", I see "OS(C: ) 424GB free of 461GB" under the "Devices and drives" section (and this is the only item there). What happened to the missing 51GB? Is this a manufacturing mistake? 

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5 Replies
JOcean
4 Ruthenium

Re: XPS 15 has only 461GB SSD instead of 512GB

Not a mistake at all, and a question that is puzzling to many users. It has to do with what manufacturers call a Gigabyte and Binary Bytes. This link should help

https://forums.crucial.com/t5/Crucial-SSDs/Why-does-my-SSD-show-up-as-smaller-than-advertised/ta-p/1...




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jphughan
5 Tungsten

Re: XPS 15 has only 461GB SSD instead of 512GB

@JOcean's answer accounts for the majority of the discrepancy, although a SSD with 512GB of capacity according to decimal definitions where 1GB = 1000MB (and 1MB = 1000KB, and so on) should have a bit over 470GB of capacity according to binary definitions where 1GB = 1024MB (2^10).  The other piece of the puzzle is that your SSD has a few hidden partitions that are required for booting an OS, including an EFI partition, MSR partition, and likely a Windows Recovery Tools partition that gets used for situations like Automatic System Repair.  Dell might also have added a partition for diagnostics (although those are embedded into the firmware these days anyway) and/or a factory restore image and restore utility.

If you're thinking that this difference in how a gigabyte is defined is confusing and annoying, you're absolutely correct.  The problem is that the binary definition is typically considered "right", but storage vendors (CD/DVD, Blu-ray, and hard drives) all use the decimal version -- and because the decimal version always returns higher numbers, none of them would be willing to change.  If all of your competitors are selling a "512GB SSD", would you want to be the one that labels it a "~470GB SSD" even though it has exactly the same capacity?  Of course not, because most consumers will think your SSD is smaller.  Same goes for optical media, where a 4.7GB blank DVD is actually 4.38GB according to the binary definition, but nobody wants to sell 4.38GB DVDs.  Incidentally, Apple a few years ago decided to change Mac OS around so that it now reports capacity in the decimal format, aligning with the way they describe the hard drives in their laptops, but that's the only OS I know of that works that way.

krunchynator
1 Nickel

Re: XPS 15 has only 461GB SSD instead of 512GB

Ok then...so as you said, according to the conversion 512GB decimal should be over 470GB binary, but the discrepancies between ~470 and 461GB are due to default system partitioning etc?

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jphughan
5 Tungsten

Re: XPS 15 has only 461GB SSD instead of 512GB


@krunchynator wrote:

Ok then...so as you said, according to the conversion 512GB decimal should be over 470GB binary, but the discrepancies between ~470 and 461GB are due to default system partitioning etc?


Correct.  If you open something like Windows Disk Management, the bottom half of the main (center) display area will show your drive's partition map.  I'm going to guess you'll have a Windows Recovery partition of around 500-750MB somewhere as well as a multi-GB Dell Recovery partition that would contain your factory restore image along with the utility to actually restore it.

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snail720
1 Nickel

Re: XPS 15 has only 461GB SSD instead of 512GB

Hi, for this issue, we should first know that computers operate in binary (or base-2), which is a numeric system that only use two digits: 0 and 1. As a result, in the operating systems, the capacity is calculated on a one-step basis every 1024, so every 1024MB is 1GB, and every 1024GB is 1TB. But the hard disk manufacturers calculate the capacity on a one-step per 1000, that is to say, every 1000MB equals 1GB and every 1000GB equals 1TB, which leads to the “reduction” of SSD capacity.

Besides, you can fix "SSD reporting wrong capacity" by resetting the Virtual Memory paging file, the size of the Virtual Memory in the computer is exactly how much space it takes up in the hard disk.

Or you should notice whether there are an unallocated space on the SSD drive in Disk Management, if there are, you need to create a new partition on it to make it show full size in File Explorer.

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