The following table lists various hard disk and SSID form factors and gives their actual size in millimetres.
| Factor | Profile | Platter Size (mm) | Width (mm) | Depth (mm) | Height (mm) | Comment |
|---|---|---|---|---|---|---|
| 5.25″ | Full-Height | 130.05 | 146.05 | 203.2 | 82.55 | All drives in early 1980s; Large capacity drives with many platters as late as the mid-1990s |
| 5.25″ | Half-Height | 130.05 | 146.05 | 203.2 | 41.4 | Early 1980s through early 1990s |
| 5.25″ | Low-Profile | 130.05 | 146.05 | 203.2 | 25.4 | Quantum Bigfoot, mid-to-late 1990s |
| 5.25″ | Ultra-Low-Profile | 130.05 | 146.05 | 203.2 | 19.05 | Quantum Bigfoot, mid-to-late 1990s |
| 5.25″ | Ultra-Low-Profile | 130.05 | 146.05 | 203.2 | 20.32 | Quantum Bigfoot, mid-to-late 1990s |
| 3.5″ | Half-Height | 63.5 | 101.6 | 146.05 | 41.4 | High-end, high-capacity drives |
| 3.5″ | Half-Height | 76.2 | 101.6 | 146.05 | 41.4 | High-end, high-capacity drives |
| 3.5″ | Half-Height | 95 | 101.6 | 146.05 | 41.4 | High-end, high-capacity drives |
| 3.5″ | Low-Profile | 63.5 | 101.6 | 146.05 | 25.4 | Industry standard, most common form factor for PC hard disks |
| 3.5″ | Low-Profile | 76.2 | 101.6 | 146.05 | 25.4 | Industry standard, most common form factor for PC hard disks |
| 3.5″ | Low-Profile | 95 | 101.6 | 146.05 | 25.4 | Industry standard, most common form factor for PC hard disks |
| 2.5″ | 19 mm Height | 63.5 | 69.85 | 100.08 | 19.05 | Highest-capacity 2.5″ drives, used in full-featured laptop systems |
| 2.5″ | 17 mm Height | 63.5 | 69.85 | 100.08 | 17.02 | Mid-range capacity drives used in some laptop systems |
| 2.5″ | 12.5 mm Height | 63.5 | 69.85 | 100.08 | 12.45 | Low-capacity drives used in small laptops (subnotebooks) |
| 2.5″ | 9.5 mm Height | 63.5 | 69.85 | 100.08 | 9.4 | Lowest-capacity drives used in very small laptops (mini-subnotebooks) |
| PC Card | Type I | 45.72 | 54.1 | 85.6 | 3.3 | Not used for hard disks |
| PC Card | Type II | 45.72 | 54.1 | 85.6 | 5.08 | Smaller-capacity expansion hard disks for laptops and consumer electronics |
| PC Card | Type III | 45.72 | 54.1 | 85.6 | 10.41 | Higher-capacity expansion hard disks for laptops |
| Compact | Type I | 25.4 | 42.93 | 36.07 | 3.3 | Smaller-capacity flash cards for digital cameras, hand-held computers and consumer electronics; not used for hard disks (yet) |
| Compact | Type II | 25.4 | 42.93 | 36.07 | 5.08 | Larger-capacity flash cards and hard disks for digital cameras, hand-held computers and consumer electronics |
| SD (Secure data) |
n/a | 32 | 24 | 2.1 | Digital cameras, MP3 players and many other devices. Available in a variety of capacites:-
Standard SD: 4 MB to 4 GB |