# Please confirm this:  10 GB is 10,240 BINARY megabytes.

**URL:** <https://boards.straightdope.com/t/please-confirm-this-10-gb-is-10-240-binary-megabytes/287123>\
**Category:** Factual Questions\
**Created:** [January 28, 2005, 4:17pm UTC](https://boards.straightdope.com/t/please-confirm-this-10-gb-is-10-240-binary-megabytes/287123 "2005-01-28T16:17:31Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![RumMunkey](https://avatars.discourse-cdn.com/v4/letter/r/b19c9b/32.png) [@RumMunkey](https://boards.straightdope.com/u/RumMunkey)\
**Post date:** [January 28, 2005, 4:17pm UTC](https://boards.straightdope.com/t/please-confirm-this-10-gb-is-10-240-binary-megabytes/287123/1 "2005-01-28T16:17:31Z")

</div>

Going to partition a disk with fdisk. Can somebody please confirm that if I tell it to partition at **10,240 MB** , I will get a **10 GB** partition?

I’m still a little shaky on Binary vs. Decimal GBs, and who uses what.  
Many thanks.

---

<div class="post-metadata">

**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\
**Post date:** [January 28, 2005, 4:22pm UTC](https://boards.straightdope.com/t/please-confirm-this-10-gb-is-10-240-binary-megabytes/287123/2 "2005-01-28T16:22:52Z")

</div>

Yes, 10,240MB is exactly 10GB.

(And of course 1MB = 1024 KB and 1KB = 1024 Bytes.)

---

<div class="post-metadata">

**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\
**Post date:** [January 28, 2005, 5:03pm UTC](https://boards.straightdope.com/t/please-confirm-this-10-gb-is-10-240-binary-megabytes/287123/3 "2005-01-28T17:03:40Z")

</div>

See [binary prefix](http://en.wikipedia.org/wiki/Binary_prefix).

---

<div class="post-metadata">

**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\
**Post date:** [January 28, 2005, 5:17pm UTC](https://boards.straightdope.com/t/please-confirm-this-10-gb-is-10-240-binary-megabytes/287123/4 "2005-01-28T17:17:14Z")

</div>

The problem occurs when people use decimal measures in a binary environment. One example: putting “4.7 GB”, meaning 4 700 000 000 bytes, on data-storage media (DVD-Rs) where it should be “4.3 GB”, meaning 4.3 x 1024[sup]3[/sup] (i.e. 4.3 x 1,073,741,824) bytes.

The IEC has gotten around this confusion by specifying a new set of prefixes for binary multiples. The binary prefix corresponding to giga would be “gibi” (Gi), from “giga binary”. GB would then mean exclusively 1 000 000 000 bytes, and GiB would be 1,073,741,824 bytes.

Wikipedia on the subject of binary prefixes: [http://en.wikipedia.org/wiki/Binary\_prefix](http://en.wikipedia.org/wiki/Binary_prefix)