Hacker News Reader

Comment by sspiff | Hacker News Reader

    2^10 = Kilo ~ 10^3
    2^20 = Mega ~ 10^6
    2^30 = Giga ~ 10^9
    2^40 = Tera ~ 10^12

This is wrong - power-of-two magnitudes are called kibi-, mebi-, gibi- and tebibytes. Kilo, Mega, Giga and Tera are prefixes used by the SI unit system, and denote powers of ten.

The confusion comes from Microsoft using power of two numbers in calculations, but SI power of ten prefixes in labels.

A kilobyte is 1000 bytes, not 1024 bytes.

View on HN

From what I found in Wikipedia, the "kibi"-family of prefixes was not defined before 1998. There's a lot of computer history before (and after!) that establishing the use of kilo for 2^10. Calling this wrong outright is historyless.

Perhaps instead we could say: This is a funny artifact of history, and it is contrary to the long standing SI-definition of kilo as 10^3. We have since tried correcting that mistake by introducing the prefixes kibi-, mebi-, etc. A better table could say:

    kibi = 2^10 ~ 10^3 = kilo
    ...

I never hear anyone use the -bi units unless they're trying to be clever, and I'm fairly sure at most storage devices use the power-of-ten units. Am I alone in that?

Storage devices use the power of 10 units correctly.

My 6TB drive has 6001175126016 bytes.

Windows probably still reports that as 5.5TB, although many Linux GUI tools now correctly say 5.5TiB, or 6TB.

(Being clever should be encouraged!)

That's even worse, because they're intentionally preying on the ignorance in an attempt to make the devices appear to have more space than they actually do.

It depends on the scale. I once got into a discussion that devolved into Tebibytes vs Terabytes for a project. The UI defaulted to TiB but offered a TB option if needed.

If the system has 100 Terabytes of storage - that's a significant difference.

TiB won out btw.

I agree, the "=" (equal) and "~" (approximately) are the wrong around, it should read:

    2^10 ~ Kilo = 10^3
    2^20 ~ Mega = 10^6
    2^30 ~ Giga = 10^9
    2^40 ~ Tera = 10^12

Or, to use the Ki, Mi, etc.

    2^10 = Kibi ~ Kilo = 10^3
    2^20 = Mebi ~ Mega = 10^6
    2^30 = Gibi ~ Giga = 10^9
    2^40 = Tebi ~ Tera = 10^12

As I remember it everyone used to do this (at least in the 90s and early 00s). If I recall correctly Apple only switched to power of ten in 10.6 which is quite recently. I suppose Microsoft may be the one causing confusion today as they keep the user facing power of two system alive (?)

It's possible that other systems did the same. I think the impact of Microsoft's decision to use this labeling is by far the greatest, though, given the spread and popularity of Windows for the past 25-30 years.

* Brought to you by, and paid for in full, the Hard Drive Manufacturers Association: "Bringing you quality hard drives that definetly aren't falsely advertised since 1956"

Obligatory Xkcd https://xkcd.com/394/

-1 points? no sense of humour

Reply on news.ycombinator.com