Hi Dan, Data storage units are a bit of a can of worms. The problem lies in common-usage vs. international standards. There are also 'old' and 'new' standards for unit abbreviations.
METRIC vs BINARY UNIT GUIDE Essential reading before continuing... < http://www.romulus2.com/articles/guides/misc/bitsbytes.shtml > RELEVANCE TO USERS There are a few reasons for showing filesize: -setting an expectation of time-to-download -setting an expectation of filesize (perhaps preferable for users on fixed usage plans) -inferring quality (assuming bigger file = better 'quality') As connection speeds tend to be in kilobits per second (kbps), then filesize _may be easier to convert to 'time-to-download'. (Although download speed uses metric notation while data storage values tends to use binary notation). The discrepancy between data transfer speed (metric) and filesize (mostly binary) is likely to be the root cause of the unit abbreviation confusion. I'd recommend MiB/MB for files greater than 1MiB/MB, and KiB/kB for files less than 1MiB/MB. If a single webpage offers alternative quality options, say for Quicktime media files, listing the download options with filesizes using the units may make it easier for the user to choose an appropriate option. Listing options in a meaningful order, e.g. from smallest-to-largest filesize will also help. (At all costs avoid ambiguous labels such as 'High' or 'Low' which could equally relate to connection speed or quality.) FILE SIZES UNDER MAC vs WINDOWS To add insult to injury, Mac and Windows operating systems use different systems when calculating filesize. Windows 2000 (File Properties) -binary: 1MiB (mebibyte) = 1024 KiB (kibibytes) Mac 0S X (File Info) -metric: 1MB (megabyte) = 1000 KB (kilobytes) SUMMARY Given the relative number of Mac and Windows users (more Windows users) and referring to the new IEC standards, the 'correct' unit abbreviation *should be* mebibytes (MiB) or kibibytes (KiB), however this flies in the face of common practice that refers to the 'old' standards of MB and KB. Toss a coin? ><a href="file.pdf">Some file (PDF 0.1MB)</a> > >My inclination is to use MB (Megabytes) where appropriate (ie. if the file is >greater than 0.01MB), and KB (Kilobytes) for files less than 0.01MB. My >reasoning is that more users can grasp the concept of a Megabyte (think floppy >disks, flash drives, some MP3 players) than they can a kilobyte, kilobit or >megabyte. > >My only concern would be that most sites seem to use (ambiguosly) one of the >kb varieties. -- Andy Kirkwood | Creative Director Motive | web.design.integrity http://www.motive.co.nz ph: (04) 3 800 800 fx: (04) 970 9693 mob: 021 369 693 93 Rintoul St, Newtown PO Box 7150, Wellington South, New Zealand ****************************************************** The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help ******************************************************
