I just got a new Lenovo Laptop which has been installed with Windows 7 and is supposed to have 250 GB hard disk.
Windows 7 reports that the hard disk drive has two parts: 221 GB C: and 9.76 GB Lenovo Recovery. The sum of the two parts is 230.76 GB.
If I remember correctly, if divide 250 GB by 1024 three times, I will get 232.8 GB, which should be what the OS reports as the hard drive size. But why the sum 230.76 GB of the two parts of hard drive is still smaller than 232.8 GB?
Because NTFS by design uses a piece of your volume for a MFT (Master File Table) which holds file names, creation dates, access permissions, and contents as metadata. The bigger the volume, the bigger the chunk NTFS will need.
Actually. This is because harddrive manufacturers conform to the 1MB = 1,000 KB rule and your OS uses the 1MB = 1,024 KB rule.
This would probably account for most of your lost space. Its normal. You will NEVER buy a drive that is the size it specifies, ever. I looked in to it myself not too long ago :)
Unfortunately, life's hard and this is one of those things that annoys people non stop.
At least you are smart and understand that there is a conversion that needs to be made.
The "extra" space is usually used up by the allocation table, meta data and various other items that just make it work without you needing to think of it... it is nothing to worry about.
If you want to make 100% sure you have the correct drive, go in to device manager and expand hard drives, find the model number and Google it. If it reports the correct drive (which it should) there shouldn't be anything to worry about.
A chunk of your loss at least is due to the partition table eating it's entire track--a horribly inefficient legacy we are left with.
A part of the issue with advertised harddrive space and actual harddrive space is down to the fact that harddrives in shops are advertised with storage information in Decimal (Base 10) as opposed to how computers understand storage, which is in Binary (Base 2).
Well, let's look at binary figures compared to decimal. These become apparent when you indicate the base figure (sub 2 for binary and sub 10 for decimal)
JEDEC, who sets the Global Standards for the Microelectronics Industry uses the binary definitions of Megabyte and Gigabyte which is exactly how computers generally would see things withinin programming etc. JEDEC states that:
A multiplier equal to 1024 (210).
A multiplier equal to 1 048 576 (220 or K2, where K = 1024).
As you can see, each step up (byte to kilobyte, kilobyte to megabyte...) is in multiples of 1024.
Harddrives are sold in decimal storage figures and these are different.
In decimal:
As you can see, each step up (byte to kilobyte, kilobyte to megabyte...) is in multiples of 100010.
IEEE/ASTM SI 10‑1997 states that the practice of stating that 1 Megabyte = 1024 kilobytes frequently leads to confusion and is to be deprecated. Further confusion results from the popular use of a "megabyte" consisting of 1 024 000 bytes to define the capacity of the familiar "1.44‑MB" floppy disk. An alternative system is found in Amendment 2 to IEC 60027‑2: Letter symbols to be used in electrical technology - Part 2, and the IEC states that figures represented in base 2 are to be referred to as kibibyte or mebibyte or gibibyte etc.
Where you are short changed is in the following:
Let's say all your files to be stored in that harddrive are exactly 1MB (Base 2) each in size. With 1TB spare:
You should be able to fit 1,048,576 files on a 1TB drive. But you can't.
You are actually only able to fit 953,674 files.
Things are also bad when you are storing digital videos. Let's say at 1GB (Base 2) each. With a 1TB (advertised space) harddrive:
You should be able to fit 1,024 files
You are actually only able to fit 931 files (90 files short)
So, as a quick reference to show the amount that the actual values differ compared to the advertised for each common referenced value:
A case in point is that a hard drive in my computer, advertised at 2TB in size, is actually 1863GB in size according to my computer instead of 2048GB. That is 185GB short (92.5GB per advertised Terabyte).
It could just be the manufacturer rounding the hard drive size to the nearest whole gigabyte. If we start with what Windows shows and calculate what that work out to in billion bytes:
232.8 * 2^30 / 10^9 = 249.9671 million bytes
So they just rounded the marketing size to 250, cause whose going to miss 0.0329 million bytes.
If you can get the module number of the hard drive and get it's detailed specs and find it's sector count you can determine what the actual capacity of the drive really is.
