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Possible Duplicate:
Why is the effective hard drive size lower than the actual size?

I just purchased a Dell Inspiron 1410 without OS. In the BIOS, it shows 320 GB of hard disk space. After I installed Windows 7 Ultimate, only 299 GB total hard disk space is shown. I only got one partition. I run a partition manager, it shows only 299 GB, without any partition that has the other 20 GB.

Can somebody try to explain what had happen? What will I do so I can use all of the 320 GB.

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2 Answers2

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The BIOS (or the HD manufacturer) is measuring with 1 GB = 109 bytes = 1.000.000.000 bytes.

The Windows file dialog seems to count in GibiBytes, where 1 GiB = 230 bytes = 1.073.741.824 bytes

Checking the numbers, 299 * 230 is approximately 320 * 109.

Oliver Salzburg
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Anders Lindahl
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Basically a 320GB disk isn't 320GB, it's to do with the mixed use of 1000 and 1024 (210) between marketing and operating system, never expect the full amount OK.

Oliver Salzburg
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Chopper3
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    actually, a 320GB disk is 320GB, just read the [units(7) man page](http://www.kernel.org/doc/man-pages/online/pages/man7/units.7.html) – alexanderpas Jun 16 '10 at 19:02
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    It's not a mix-up between marketing and operating system, it's a mix-up between the metric system and lazy programmers. – endolith Sep 04 '10 at 20:10