Quintillion bytes to terabytes

I am trying to convert 2.5 quintillion bytes to terabytes (IBM's estimate on the amount of data produced daily), could someone check if my calculations are correct?

1 Terabyte is 1000 Gigabytes
1 Gigabyte is 1000 Megabytes
1 Megabyte is 1000 Kilobytes
1 Kilobyte is 1000 Bytes

1 Quintillion is $10^{18}$

2.5 Quintillion is $2.5 x 10^{18}$

1 Terabyte is $10^{12}$ bytes

How many terabytes is it then? How do you work this out? Is this correct?

$2.5x10^{18}$ / $10^{12}$ = 2,500,000 Terabytes?

This sounds like an awful lot to me? Does this sound/look correct?

Your calculation is correct. There are two different usages of kilo/mega/gigabytes, one with factors of $1000$ and one with factors of $2^{10}=1024$. Since you're dealing with a rather rough estimate, the difference is probably not important.
• It should be noted that sometimes one tries to distinguish the $1024$ conversion from the $1000$ conversion using "kibibytes", "gibibytes", etc. Not that I approve of the chosen terms for the units... :) Mar 17 '16 at 11:23