How much can a cassette tape hold in data storage terms?

[dragos240]

Cassettes used to be used for data storage. How much could today's cassette tapes hold, the ones you buy in stores that you can write over. How much is on one of them?

[TheNerdAL]

"The most common format is the C90 (2 sides of 45 minutes - usually actually about 47 minutes...), then the C60 (2 x 30minutes). However there are also C120's out there that hold an hour per side, and all sorts of commercial tapes that are cut to length for specific uses. I think they used to make 15 minute cassettes for computers that used cassette for storage.
Some formats were also specifically designed to hold the contents of a CD or a vinyl album, so just to confuse matters, some manufacturers made 74 minute tapes too (37 minutes a side). It is most likely that the tapes you will come across will be C90's but it is by no means a certainty..."

http://answers.yahoo.com/question/index?qid=20090703125946AA1wdKz

[yabbadabbadont]

Actually, it would depend upon the baud rate used (in addition to the length of tape). The way data was stored on cassette tape (for home computers anyway) was basically by recording the audio equivalent of modem squeal.

[unplugged23]

From what I remember, RAM used to be stored on a kind of casette tape. I don't think anyone was every able to get more than a few hundred kb's out of one, this is why we started developing differnt mediums for storage and memory.

[MadCow108]

cassettes are still in massive use for long term data storage, every computing clusters uses them.
they have a very high lifetime (~20-50 years) compared to other storages.

modern cassettes hold around 500gb of data

[BuffaloX]

Back in the day when we actually used cassette tapes on a regular basis, their capacity was sufficient for the time, but by todays standard the capacity would be minuscule.
I had a C64 which was probably among the worst Cassette systems available.
A game could take as much as 20 minutes to load, and the capacity of the system was only 64KB.
The tape could be read about 10 times faster, meaning a 10 time increase in capacity.
This would mean 20 min = 64KB x 10 = 640 KB
60/20 = 3 x 640 KB = roughly 2 MB.

Later we got tape-drives designated for data storage, but these were not ordinary cassettes, but could store 40 - 120 MB.

The densest affordable storage that came later was DAT drives, which was still somewhat expensive, The capacity of a DAT tape is about the same as a CD, but I may remember it incorrectly.