When is a megabyte not a megabyte?

[Mikuro]

I just noticed that Apple has changed how it measures megabytes in OS X. Now it calculates 1MB as 10^6 bytes, not 2^20 like it's been for the past 30 years. Apparently they changed it in Snow Leopard.

I think this is kind of annoying. I kept thinking Handbrake was screwing up my file sizes making them 35 megabytes too big to fit on a CD.

Now I'll have to go to a calculator when I want to know the real size of things. Before I could easily tell the size by EITHER method at a glance, by looking at the calculated MB size or the total byte size, both of which were displayed in the Get Info dialog.

 

[ElDiabloConCaca]

Yep, this is true:

http://blog.macsales.com/1852-snow-...gigabytes-and-megabytes-and-kilobytes-as-well

I don't know of any way to "go back" to the old calculation in Snow Leopard, and I feel your pain -- as a developer, I had to change some of my workflows in order to account for the different representation.

Good ol' UNIX command-line never failed me, though, so that's where I look for the "real" size (du and df are lifesavers).

It is weird to be able to fit almost 800 "MB" on a CD, isn't it?

 

[ScottW]

Interesting!!!

You know, stupid ol me, I always thought drives where smaller because of "formatting". Now that I think about it, indeed it is all about formatting, not the overhead for the drive formatting, but the calculation format.

It is interesting, that all these years, drive manufacturers have got away with this number discrepancy and it's not been a big deal.

I wonder if this has anything to do with SSD? I'm sure Apple is tired of people complaining their 64GB SSD has less space on it than what is advertised, specially on a MacBook Air and drive space is precious commodity. I want my extra blocks!!! Argh, you already have them, it's just a number formatting issue.

Well, it's all relative anyhow. Since I started using Clusters to compress my drive and free up precious SSD space, Clusters reports a savings of 79GB, but since the actual file label sizes don't change, yet space is cleared up on the drive, that number it has calculated seems a little unverifiable. But, I haven't looked into the issue deeper to determine if there is a way to find out or not.