List of floppy disk formats

This is a list of different floppy disk formats.

For a more in-depth textual description of some of these formats, see Floppy disk variants.

8-inch, 5+1⁄4-inch, and 3+1⁄2-inch floppy disks

Physical formats
Floppy disk physical characteristics
(capacity and tracks are nominal, per side)
SizeDensityTrackstpibpiCoercivityUnformatted capacity per side
21⁄2 inch[1][2]Single16[1][2]48[1]64 kB[1][2]
3 inchSingle401008,946250 kB
Double80500 kB
31⁄2 inchSingle40[3]67.5[3]8,650[3]665 Oe250 kB
Double 801358,717665 Oe[4]500 kB
High8013517,434720-750 Oe1,000 kB
Extended8013534,868900 Oe2,000 kB
Triple[5]240[6]406.5[6]36,700[6]6,500 kB
51⁄4 inchSingle/Double40485,876300 Oe250 kB
Double (FileWare)8062.5851 kiB[7]
Quad77100300 Oe500 kB (Micropolis-compatible)
Quad80965,922300 Oe500 kB
High80969,646600 Oe833 kB
8 inchSingle77483,268-3,408 300 Oe1,000 kB
Double 6,816 1,000 kB

Logical formats

Throughout the 1970s and 1980s, many different logical disk formats were used, depending on the hardware platform.

Common floppy disk formats, logical characteristics by platform
PlatformSizeDensitySidesTracks/ sideSectors/ trackBytes/ sectorCapacityrpmEncodingNote
Acorn 51⁄4 inch Single 1 40 10 256 100 kB 300 FM
80 200 kB
Double 1 40 16 256 160 kB MFM
80 320 kB
2 640 kB
31⁄2-inch (90 mm) Double 2 80 16 256 640 kB 300 MFM Format L: MOS (Electron, Master Compact)
5 1024 800 kB
  • Format D: Arthur, RISC iX
  • Format E: RISC OS
High 10 1,600 kB Format F: RISC OS 3 and later. Archimedes models before the A5000 require an upgraded floppy drive.
Agat 51⁄4 inch Double 2 80 21 256 840 kB 300 MFM [NB 1]
Amstrad CPC/PCW 3-inch Double 1 40 9 512 180 kB 300 MFM Single head drive, but double-sided floppy discs (total of 360 kB per floppy)
Amstrad PCW8512/9512 3-inch Double 2 80 9 512 720 kB 300 MFM 720 kB mode uses both sides - ensure disc inserted correct way up.
Apple II 51⁄4 inch Double 1 35 13 256 113.75 kB 300 GCR [NB 2]
1 16 140 kB
31⁄2-inch (90 mm) Double 1 80 Variable (8-12) 512 400 kB 394 - 590 GCR [NB 3]
2 800 kB
High 2 80 18 512 1,440 kB 300 MFM [NB 4]
Apple Lisa 51⁄4-inch FileWare Double 2 46 Variable (15-22) 512 851 kB 218 - 320[8] GCR
Apple Lisa 2/Macintosh XL,

Macintosh

 31⁄2-inch (90 mm) Double 1 80 Variable (8-12) 512 400 kB 394 - 590 GCR
Apple Macintosh 2 800 kB
High 2 80 18 512 1,440 kB 300 MFM
Atari 8-bit 51⁄4 inch Single 1 40 18 128 90 kB 288 FM [NB 5]
Double 26 128 130 kB MFM
Double 18 256 180 kB
Double 2 18 256 360 kB 300
Atari ST/TT/Falcon 31⁄2-inch (90 mm) Double 1 80 9 512 360 kB 300 MFM
2 720 kB
High 18 1,440 kB
Coleco ADAM 51⁄4 inch Double 1 40 8 512 160 kB 300 MFM
Commodore (8-bit) 51⁄4 inch Double 1 35 Variable (17-21) ZCAV 256 170 kB 300 GCR [NB 6]
2 340 kB
Quad 1 77 Variable (23-29) ZCAV 521 kB
2 1,042 kB
31⁄2-inch (90 mm) Double 2 80 10 512 800 kB MFM  
Commodore Amiga 51⁄4 inch Double 2 40 11 512 440 kB[NB 7] 300 MFM [NB 8]
Quad 80 880 kB[NB 9]
31⁄2-inch (90 mm) Double 880 kB
High 19 1,520 kB GCR [NB 10]
22 1,760 kB 150 MFM [NB 8]
IBM 33FD 8 inch Single 1 77 26 128 240.5 kiB 360 FM Diskette 1[9]
15 256 277.5 kiB
8 512 296 kiB
IBM 43FD 2 26 128 481 kiB Diskette 2[9]
15 256 555 kiB
IBM 53FD Double 26 256 962 kiB MFM Diskette 2D[9]
15 512 1.08 MiB
8 1024 1.16 MiB
DEC RX01 8 inch Single 1 77 26 128 250 kB 360 FM
DEC RX02 8 inch Double 1 77 26 256 500 kB 360 FM/MFM
DEC RX50 51⁄4 inch Quad 1 80 10 512 400 kB 300 MFM
IBM PC compatibles[10] 8-inch Single 1 77 26 128 250.25 kB[NB 11][10][11][12] 360 FM [NB 12]
2 500.5 kB[NB 11][10][11][12]
Double 1 8 1024 616 kB[NB 11][11][12] MFM
2 1,232 kB[NB 11][10][11][12]
51⁄4 inch Double 1 40 8 512 160 kB[NB 11] 300 MFM  
2 320 kB[NB 11]
1 9 180 kB[NB 11]
2 360 kB[NB 11]
Quad[NB 13] 1 80 8 320 kB[NB 11] 300
2 640 kB[NB 11]
High 2 80 15 1,200 kB[NB 11] 360
31⁄2-inch (90 mm) Double 1 80 8 512 320 kB[NB 11] 300 MFM
9 360 kB[NB 11]
2 8 640 kB[NB 11]
9 720 kB[NB 11]
High 18 1,440 kB[NB 11]
21 1,680 kB[NB 11] DMF[NB 14]
82 1,720 kB[NB 11]
Extended 80 36 2,880 kB[NB 11]
MGT SAM Coupé 31⁄2-inch (90 mm) Double 2 80 10 512 800 kB 300 MFM  
NEC PC98 8-inch Single 1 77 26 128 250.25 kB[NB 11] 360 FM  
Double 2 77 8 1,024 1,232 kB[NB 11] MFM
51⁄4 inch Double 2 80 8 512 640 kB[NB 11] 360 MFM
9 720 kB[NB 11]
High 15 1,200 kB[NB 11]
77 (80)[NB 15] 8 1,024 1,232 (1,280) kB[NB 11][NB 15] [NB 15]
31⁄2-inch (90 mm) Double 2 80 8 512 640 kB[NB 11] 360 MFM
9 720 kB[NB 11]
High 15 1,200 kB[NB 11] 3-mode[NB 16][NB 15]
77 (80)[NB 15] 8 1,024 1,232 (1280) kB[NB 11][NB 15]
80 18 512 1.44 MB[NB 11] 300
Triple 240 38 512 9,120 kB 360 NEC PC-88 VA3 2TD drive only[6][5]
Osborne 1[13] 51⁄4 inch Single 1 40 10 256 100 kB 300 FM
Double 5 1,024 200 kB MFM
Sega SF-7000 3-inch Single 2 40 16 256 160 kB  ?  ? Expansion unit for SC-3000 home computer. Capacity is per side.

[14]

SHARP X68000 51⁄4 inch High 2 77 8 1,024 1,232 kB[NB 11] 360 MFM  
31⁄2-inch (90 mm)
SHARP CE-1600F,[1] CE-140F[2] 21⁄2-inch (63.5 mm)[1][2] Single (250 kbit/s, 48 tpi[1]) drive: 1, diskette: 2 (turnable)[1][2] 16 (tracks 00..15)[1][2] 8[1][2] 512[1][2] 2× 64 kB[1][2] 270[1] GCR (4/5)[1][2] Internally based on FDU-250 Micro Floppy Disk Drive Unit[1]
Thomson 51⁄4 inch Single 1 40 16 128 80 kB 300 FM Thomson UD90.070
Double 2 256 320 kB MFM Thomson DD90-320[NB 17]
31⁄2-inch (90 mm) Double 1 80 16 256 320 kB 300 MFM Thomson TO9, Thomson DD09-350
Double 2 640 kB Thomson TO8D, TO9+, Thomson DD90-352[NB 18]
Victor 9000 / ACT Sirius 1[15] 51⁄4 inch Single 1 80 11-19 (variable) 512 612 kB[16] 252-417 (variable) GCR Disks varied sectors / track and disk speed to keep consistent bit density across tracks[15]
Double 2 512 1,196 kB[16]
Tandy TRS-80 51⁄4 inch Single 1 35 10 256 88 kB 300 FM Model 1/3/4
51⁄4 inch Double 1 40 18 256 180 kB 300 MFM Model 1/3/4P
51⁄4 inch Double 2 40 18 256 360 kB 300 MFM Model 4D
8 inch Double 1 77 26 256 500 kB 360 MFM Model 2
3 1⁄2 inch (90 mm) Double 1 40 2 1280 100 kB[17] 300 FM Hard sectored, Tandy Portable Disk Drive (aka Brother FB-100, knitking FD-19)
3 1⁄2 inch (90 mm) Quad 1 80 2 1280 200 kB[18] 300 FM Hard sectored, used only in Tandy Portable Disk Drive 2
HP Portable Series 40/70 3 1/2 inch Double 2 80 16 256 630 kB 600 MFM HP 9114A
HP 9845C 8 inch Double 2 77 29 256 1.18 MB 360 MFM HP 9895A
HP 86 5 inch Double 2 35 16 256 286 kB 300 MFM HP 9130K

https://literature.hpcalc.org/community/hp9114a-om-en.pdf

http://www.bitsavers.org/pdf/hp/disc/09895-90000_9895A_Flexible_Disc_Users_Man_Sep79.pdf

https://www.manualslib.com/manual/868900/Hp-9130k.html?page=6#manual

See also
  • Zip drive (floppy-like, but incompatible medium using different technology)
  • PocketZip (floppy-like, but incompatible medium using different technology)
  • SuperDisk (floppy-like with drives also compatible with 3.5" floppy disks)
  • MO disc (floppy-like, but incompatible medium using different technology)

Notes
  1. Custom controller with unique track layout.
  2. 16 sector filesystems require a compatible disk controller (PROM update) and Apple DOS 3.3 or later.
  3. Apple II double-density 31⁄2-inch (90 mm) drives use variable sectors sizes (tracks 00-15: 12 sectors, tracks 16-31: 11 sectors, tracks 32-47: 10 sectors, tracks 48-63: 9 sectors, tracks 64-79: 8 sectors), 394 rpm to 590 rpm.
  4. Apple II high-density 31⁄2-inch (90 mm) drives require a compatible disk controller and ProDOS 8.
  5. Third party drives offer up to 1440 KB.
  6. Commodore floppy drives used a fixed rotation speed with variable sector density (see: Zone bit recording).
  7. This format was used by the Amiga 1020 external floppy drive and some third-party drives connected to the normal Amiga floppy drive bus.
  8. Though the Amiga used MFM, the format places sectors too close together for a standard IBM PC compatible floppy disk controller to read (appearing as one 5632-byte physical sector per track).
  9. Format used by rare third-party drives with quad density disks; such drives were usually switchable between 80-track and 40-track (A1520/PC-compatible) operation.
  10. Format used by third-party gcrdisk.device driver in order to use PC-standard HD floppy drives (which rotated at a fixed 300 rpm) via the Amiga floppy drive bus. The Amiga's floppy controller could not keep up with the data rate needed for MFM recording on HD floppies without reducing rotational speed, so the third party driver used an alternate GCR mode.
  11. The calculated formatted capacity is based on FAT12 format.
  12. While IBM didn't include an 8-inch floppy drive option on any of their PCs and PC DOS, MS-DOS 1.25 supported 8-inch disks and added support for higher capacities in version 2.0. MS-DOS' predecessor 86-DOS used 8-inch diskettes as well.
  13. Rare format appearing on some early PC/XT clones using quad-density disks.
  14. These variations are known as DMF diskettes, used for a time to pack more data on to each disk for software distribution.
  15. Inner 3 tracks of 8 sectors/track format are unused.
  16. The PC98 31⁄2-inch (90 mm) formats are also known as "3 Mode" floppy disks, usable on IBM PC compatibles with a 3-mode floppy drive.
  17. The two sides are managed as two independent 160 KB disks
  18. The two sides are managed as two independent 320 KB disks

    References
    1. "Model CE-1600F". Sharp PC-1600 Service Manual (PDF). Yamatokoriyama, Japan: Sharp Corporation, Information Systems Group, Quality & Reliability Control Center. July 1986. pp. 98–104. Archived (PDF) from the original on March 23, 2017. Retrieved March 23, 2017.
    2. Sharp Service Manual Model CE-140F Pocket Disk Drive (PDF). Sharp Corporation. 00ZCE140F/SME. Archived (PDF) from the original on March 11, 2017. Retrieved March 11, 2017.
    3. "PF-10" (PDF). Epson. 1984. Archived from the original (PDF) on June 21, 2020. Retrieved November 30, 2022.
    4. "Floppy Drive Tech Info". www.retrotechnology.com. Retrieved July 6, 2023.
    5. NEC μPD72070 - Floppy Disk Controller Specification Version 2.0 (PDF). 2.0 preliminary. NEC Corporation. October 1991. Archived from the original (PDF) on March 20, 2017. Retrieved March 20, 2017.
    6. "ハードウエア" [Hardware]. NEC PC-88VA (in Japanese). Archived from the original on June 18, 2017.
    7. Berry, D (September 7, 1982). Lisa Hardware Manual (PDF). Apple Computer Inc. pp. 9–1.
    8. "Apple's Twiggy Disks". www.brouhaha.com. Retrieved October 11, 2023.
    9. The IBM Diskette General Information Manual (PDF) (Reference Manual). USA: IBM. 1979. pp. 18–19.
    10. "Standard Floppy Disk Formats Supported by MS-DOS". 2.0. Microsoft. December 17, 2000. Retrieved February 5, 2020.
    11. Zbikowski, Mark; Allen, Paul; Ballmer, Steve; Borman, Reuben; Borman, Rob; Butler, John; Carroll, Chuck; Chamberlain, Mark; Chell, David; Colee, Mike; Courtney, Mike; Dryfoos, Mike; Duncan, Rachel; Eckhardt, Kurt; Evans, Eric; Farmer, Rick; Gates, Bill; Geary, Michael; Griffin, Bob; Hogarth, Doug; Johnson, James W.; Kermaani, Kaamel; King, Adrian; Koch, Reed; Landowski, James; Larson, Chris; Lennon, Thomas; Lipkie, Dan; McDonald, Marc; McKinney, Bruce; Martin, Pascal; Mathers, Estelle; Matthews, Bob; Melin, David; Mergentime, Charles; Nevin, Randy; Newell, Dan; Newell, Tani; Norris, David; O'Leary, Mike; O'Rear, Bob; Olsson, Mike; Osterman, Larry; Ostling, Ridge; Pai, Sunil; Paterson, Tim; Perez, Gary; Peters, Chris; Petzold, Charles; Pollock, John; Reynolds, Aaron; Rubin, Darryl; Ryan, Ralph; Schulmeisters, Karl; Shah, Rajen; Shaw, Barry; Short, Anthony; Slivka, Ben; Smirl, Jon; Stillmaker, Betty; Stoddard, John; Tillman, Dennis; Whitten, Greg; Yount, Natalie; Zeck, Steve (1988). "Technical advisors". The MS-DOS Encyclopedia: versions 1.0 through 3.2. By Duncan, Ray; Bostwick, Steve; Burgoyne, Keith; Byers, Robert A.; Hogan, Thom; Kyle, Jim; Letwin, Gordon; Petzold, Charles; Rabinowitz, Chip; Tomlin, Jim; Wilton, Richard; Wolverton, Van; Wong, William; Woodcock, JoAnne (Completely reworked ed.). Redmond, Washington, USA: Microsoft Press. ISBN 1-55615-049-0. LCCN 87-21452. OCLC 16581341. (xix+1570 pages; 26 cm) (NB. This edition was published in 1988 after extensive rework of the withdrawn 1986 first edition by a different team of authors. )
    12. Xerox 16/8 Professional Computer – MS-DOS OS Handbook for 8" Floppy Disks (PDF). Xerox. November 1983.
    13. Hogan, Thom; Iannamico, Mike (1982). Osborne 1 Technical Manual (PDF). Osborne Computer Corporation. p. 39.
    14. "Sega SF-7000 Super Control Station User Guide". Sega Enterprises. Retrieved February 10, 2020.
    15. "Victor 9000 Hardware Reference Manual" (PDF). Archived (PDF) from the original on January 29, 2022. Retrieved September 12, 2022.
    16. Lemmons, Phil (November 1982). "Victor Victorious". BYTE. p. 216. Retrieved October 19, 2013.
    17. Tandy Portable Disk Drive Operation Manual 26-3808. Japan: Radio Shack. 1985. p. 25.
    18. Tandy Portable Disk Drive 2 Operation Manual 26-3814. Japan: Radio Shack. 1986. p. 33.
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