In Mac OS 10.6 disk and file sizes are measured in base 10 (one kilobyte is defined as 1000 bytes, one megabyte is defined as 1000 kilobytes, etc.) in Finder and Disk Utility. Unfortunately this has created a lot of inconsistency even when working with Apple’s own programs since most of them still define file sizes in binary units (one kilobyte is defined as 1024 bytes, one megabyte is defined as 1024 kilobytes, etc.). This utility will switch the measurement of disk and file sizes in both Finder and Disk Utility back to binary units (or if the measurement has already been switched to binary units it will restore the system back to using base 10 units).
For Mac OS X Lion and later: switchDiskSizeBase v2.1
For Mac OS X Snow Leopard: switchDiskSizeBase build 11
brkirch's Blog 
will you release a Mountain Lion supported version ? 🙂
Have you tried to run the switchDiskSizeBase utility in OS X 10.8 Mountain Lion? Is it still working? Are you still supporting its development?
Thanks.
Currently switchDiskSizeBase does not work on OS X Mountain Lion. I’m working on a new version and it will probably be ready sometime this month (I’ve been working on completely changing how switchDiskSizeBase works which is why it is going to take a little longer than usual to update).
thanks a lot !!
Looking forward to the update for 10.8. Apple should give us the option for binary bytes. 😦
Thanks for your work, looking forward to a 10.8 version!
I’m second the need for Apple to support switching but that’s a discussion for another time. Looking forward to a Mountain Lion version!
Important tool. One of the main reasons for me to not switch from Leopard to Snow Leopard were the foxed up file sizes in Finder. This tools solves this problem. 🙂
This utility changed my life 🙂
You are awesome! MacRumors has a dead link, but I found this one.
Thank you, thank you, thank you…
Big thanks!
Thank you so much for the update!
YES!!! FINALLY! 😀
And it even works with XtraFinder!
Thank you so much for this, it’s awesome. The base 10 retardation of OS X was driving me crazy.
Any love for Mavericks? OS X base 10 retardation makes me as mad as imperial units! 🙂
switchDiskSizeBase v2.0 already works on Mavericks, and other than the limited column width of the size column in the Mavericks Finder making the dual display option less useful I’m not aware of any significant issues.
Would it be possible to provide an option to use the base 2 and normal unit names, like GB instead of GiB? Maybe i’m already too old, but to me kB, MB, GB always meant numbers in base 2, and these i-s are quite annoying to me
The option is there already, choose “No change” when you run switchDiskSizeBase and are asked how the Finder should display units.
Very nice!!! Works with Maverick.
Before I break my Yosemite beta, has anyone tried it there with success? Thanks 🙂
Okay, tried to install, but it failed with “Code signing test failed, try installing Xcode from the Mac App Store.” I have Xcode 6 beta installed (the only one that can be installed on Yosemite)
It also fails since the last Mavericks 10.9.5 update… 😦 with the same “Code signing test failed…”. Installing Xcode 5 doesn’t solve the issue for me in Mavericks 10.9.5.
same problem with 10.9.5. After updating Mavericks, i see this error message.
SwitchDiskSizeBase v2.0.1 works fine with the last Mavericks update 10.9.5 ! Many, many thanks for maintening this awesome app !
After installing Command Line Tools and Xcode v6.0.1, SwitchDiskSizeBase v2.0.1 does NOT work on Yosemite GM (14A379a). Looking forward to a fix soon!
Not working on Yosemite 😦
If you haven’t already, try deleting the switchDiskSizeBase application, redownload switchDiskSizeBase v2.1 and see if it still doesn’t work. If it doesn’t, what happens when you try to run it (is there an error message, and if so what does it say)?
Code signing test failed, try installing Xcode from the Mac App Store.
After restart OS, all OK. Perfect!!!
New version for El Capitan please!!!