# How to calculate the capacity of a disk drive

TanyaQ
Thread moved from the technical forums, so no Homework Template is shown
Good morning, I got a question like this-

"A hard drive has 6 platters, each platter records data on both sides. There are 3000 tracks of nine sectors each. Each sector stores 512 bytes of data. How many read/ write heads are there and what are the capacity of the drive(in Gigabytes)?"

I understand so far the read/ write heads= 2*6 =12
The capacity of the drive= 512*9*3000*12=165888000bytes

I understand to where they got this answers but its not finish as I need to get it to the gigabyte and this find the capacity of the disk. Can you please assist I don't understand ?

Delta2

## Answers and Replies

Science Advisor
Gold Member
2022 Award
I need to get it to the gigabyte
You've GOT it to the gigabyte, given the information you were given.

Why would you need more than 6 significant digits anyway?

Why do you believe that the numbers given are not exact?

Science Advisor
A gigabyte is 1,000,000,000 bytes. Does this help?

TanyaQ and Delta2
Homework Helper
Gold Member
There are two definitions for GigaByte, one is as @phyzguy says at post #3 and the other is equal to

##2^{30}=1,073,741,824## bytes.

collinsmark
Homework Helper
Gold Member
There are two definitions for GigaByte, one is as @phyzguy says at post #3 and the other is equal to

##2^{30}=1,073,741,824## bytes.
In recent years (starting at around 1998), in order to avoid confusion, new terms were created such as "gibibyte," as opposed to "gigabyte," where

1 gibibyte = 1 GiB = $2^{30}$ bytes = 1,073,741,824 bytes

in contrast to

1 gigabyte = 1 GB = $10^9$ bytes = 1,000,000,000 bytes.

However, -- and this is important --, the "correct" answer may depend on how old your textbook is. This whole kibi, mebi, gibi, tebi, pebi, exbi, zebi, and yobi naming convention wasn't universally adopted by everybody.

For the longest time, "gigabyte" might have meant 1,073,741,824 bytes, or it might have meant 1,000,000,000 bytes, and which one was chosen by the hard-drive manufacturer was whichever one made the product look better.

So my advice to you, @TanyaQ, is whichever convention you use, be sure to back it up with your definition. (Or better yet, just answer in terms of both conventions [GB and GiB] to avoid confusion. )

Last edited:
jim mcnamara, berkeman, TanyaQ and 1 other person
Homework Helper
Gold Member
Oh, and @TanyaQ,

Welcome to PF!

Delta2
TanyaQ
In recent years (starting at around 1998), in order to avoid confusion, new terms were created such as "gibibyte," as opposed to "gigabyte," where

1 gibibyte = 1 GiB = $2^{30}$ bytes = 1,073,741,824 bytes

in contrast to

1 gigabyte = 1 GB = $10^9$ bytes = 1,000,000,000 bytes.

However, -- and this is important --, the "correct" answer may depend on how old your textbook is. This whole kibi, mebi, gibi, tebi, pebi, exbi, zebi, and yobi naming convention wasn't universally adopted by everybody.

For the longest time, "gigabyte" might have meant 1,073,741,824 bytes, or it might have meant 1,000,000,000 bytes, and which one was chosen by the hard-drive manufacturer was whichever one made the product look better.

So my advice to you, @TanyaQ, is whichever convention you use, be sure to back it up with your definition. (Or better yet, just answer in terms of both conventions [GB and GiB] to avoid confusion. )
Thank you

collinsmark
TanyaQ
Thank you
I never know all these. Now I do. Thank you very much

Delta2
TanyaQ
A gigabyte is 1,000,000,000 bytes. Does this help?
Sooooo much. Thank you

Delta2
TanyaQ
A gigabyte is 1,000,000,000 bytes. Does this help?

TanyaQ
Yes