ARCHIVED: What is the storage capacity of my floppy diskette?

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The storage capacity of a floppy diskette depends on whether it is a high-density or double-density diskette, and whether it is a 3 1/2" diskette or a 5 1/4" diskette. Using standard DOS formats, double-sided diskettes have the following capacities:

Type Capacity
3 1/2" double density 720KB
3 1/2" high density 1.44MB (1440KB)
3 1/2" extra high density 2.88MB (2880KB)
3 1/2" LS 120 high capacity FDD
120MB (requires LS 120 drive)
5 1/4" double density 360KB
5 1/4" high density 1.2MB (1200KB)

Keep in mind that the diskettes have to be formatted properly, at the proper density. It is possible, for instance, to format a 3 1/2" double-density diskette at high density and store 1.44MB of data on it, but this is a risky thing to do, since the media was not designed to store data at such high densities.

The best way to identify diskettes is by relying on printed markings. Double-density diskettes are usually marked "DD", "2DD", or "2S2D". High-density diskettes are marked "HD", "2HD", or "2SHD". Extra high density diskettes (which are rare and require a computer with a compatible drive, having a capacity of 2.8MB) are usually marked "ED".

Double-density 5 1/4" diskettes usually have a hub ring, while high-density diskettes generally do not (although there may be exceptions). High-density 3 1/2" diskettes have a square hole on the diskette shell in the top left corner (when the diskette is oriented face up with its shutter down). Double-density 3 1/2" diskettes lack this hole. Extra high density diskettes have holes that are located lower than the ones on high-density diskettes.

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Last modified on 2018-01-18 09:12:00.