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I noticed that MacOS (10.6) makes a decimal conversion for file sizes, instead of binary:

file size conversion on MacOS

Is there any way to force it to make binary conversions instead in Finder? Because my mind kinda works in powers of 1024, regarding the file sizes.

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Are you talking about in Terminal or Finder? – conorgriffin Feb 5 '11 at 18:50
@Griffo in Finder.. – Lipis Feb 5 '11 at 18:55
This is the "proper" conversion. K stands for Kilo, which means 1000, not 1024. – phihag Feb 5 '11 at 22:56
@phihag actually you're right.. :D – Lipis Feb 5 '11 at 23:43
up vote 5 down vote accepted

Unfortunately, you can't. See this apple support document which explains that since 10.6 they started measuring storage capacity according to the decimal GB (Gigabyte) rather than binary GiB (Gibibyte) values. This matches up with how hardware manufacturers measure the capacity of storage devices. OS X 10.5 and earlier, along with iPhones, iPads and iPods still use binary measurements.

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Binary GB values are called GiB (gigibytes). – rightfold Feb 6 '11 at 1:25
Actually it's gibibyte but thanks for making me realise I'd put GB instead of GiB. Corrected now. – conorgriffin Feb 6 '11 at 1:37
Looks like there is nothing we can do unless some third party apps that promising this... but I'm not really willing to even try them..! Both answers are right.. but there can be only one :D – Lipis Feb 6 '11 at 1:43
Well Apple did get the nice side effect of making everybody think that Snow Leopard suddenly saved them a few GiBs over Leopard! Unless you're working to very particular file size constraints for some reason it's not that big a deal. On the upside it makes a 500GB disk a 500GB disk instead of a 466GiB disk – conorgriffin Feb 6 '11 at 1:49

This was changed when OS X 10.6 was released. It is not user-configurable, unfortunately.

Related xkcd (comic) strip:

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At least give the option to change it dear Apple! Of course people are not asking any more why my 200GB has only 186GB.. but stil.. – Lipis Feb 5 '11 at 18:59
@Lipis I agree! Then again, Apple isn't famous for user-configurable options. When I need that, I switch to my Linux VM. – Nathan Greenstein Feb 5 '11 at 19:01

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