Thread: Confusion over units (need help with conversion formulas)

1. In a 1 Terabyte (TB) hard disk what is its real capacity? is it measured in GB or GiB, and what is the formula?

A seedbox with a connection of 100 Mbps , what is "real" value?
is it 100/8= 12,5 MB/s is this the "real" value? or is it the MiB/s one, whats is the formula it? is it 12,5/1,024= 12,207 MiB/s?

2. A 1 TB hard drive has an actual formatted capacity of 931 GB.
My formula involved going to "System Properties" and checking.

3. You can use google to calculate these things.

1 TB = 1024gigabytes

But, hard drive manufacturers count a tb as 1000gb, and a gigabyte as 1000mb, etc. which is why the actual size ends up being smaller (931gb says clocker).

1 000 000 000 000 bytes = 931.322575 gigabytes

100mbps = 12MB/s

Little b = bits, Big B = bytes

4. The "real" capacity also depends on the formatting used. You get more usable space if it's formatted fat32 than say NTFS (not by much) but then you're giving up performance points. To show what Tess means here is my "Music and Pics" drive. If you look at the total capacity it shows 750,153, 363,456 bytes so it is a 750 GB drive according to the manufacturer but the useable space in NTFS is 698 GB. The larger the drive the more space you "lose" due to formatting as well.
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5. Originally Posted by clocker
A 1 TB hard drive has an actual formatted capacity of 931 GB.
My formula involved going to "System Properties" and checking.
Originally Posted by tesco
You can use google to calculate these things.

1 TB = 1024gigabytes

But, hard drive manufacturers count a tb as 1000gb, and a gigabyte as 1000mb, etc. which is why the actual size ends up being smaller (931gb says clocker).

1 000 000 000 000 bytes = 931.322575 gigabytes

100mbps = 12MB/s

Little b = bits, Big B = bytes
These. It's a good marketing tactic.

As Detale said, some of the "real" capacity is also used to store filesystem data (the NTFS MFT, free space bitmap, etc.) and therefore isn't available either.

6. Usually when you are working with memory or a CPU register, you use a power of 2. In other areas, it is a power of 10. Back in the day HDD manufacturers use to use a power of 2 to show capacity, they switched some time back for whatever reason.

7. Originally Posted by sandman_1
Usually when you are working with memory or a CPU register, you use a power of 2. In other areas, it is a power of 10. Back in the day HDD manufacturers use to use a power of 2 to show capacity, they switched some time back for whatever reason.
One switched so that they could advertise larger sizes than competitors, forcing the rest to change as well or lose sales, and it stuck.

8. Originally Posted by tesco
Originally Posted by sandman_1
Usually when you are working with memory or a CPU register, you use a power of 2. In other areas, it is a power of 10. Back in the day HDD manufacturers use to use a power of 2 to show capacity, they switched some time back for whatever reason.
One switched so that they could advertise larger sizes than competitors, forcing the rest to change as well or lose sales, and it stuck.
I thought it was mainly for the masses, easier to comprehend a power of 10 than 2. But I am sure you are also right in your point.

rhemux wrote:

A seedbox with a connection of 100 Mbps , what is "real" value?
is it 100/8= 12,5 MB/s is this the "real" value? or is it the MiB/s one, whats is the formula it? is it 12,5/1,024= 12,207 MiB/s?
You are doing a conversion here from bits to bytes. 8 bits in a byte so you divide by 8 to get the rate in bytes/second.

Check this out:

I have a Seagate ST31000528AS. The spec's show, Guaranteed Sectors 1,953,525,168, and 512 bytes/sector which comes to 1,000,204,886,016 bytes (1 TB).

I have it formatted to NTFS and Windows 7 reports the size is 931.51. 1,000,204,886,016 bytes / 2^30 = 931.51GB.

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