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Form Factor Comparison
For ease of comparison, the summary table below lists all of the standard internal hard
disk form factors with their dimensions, typical platter sizes
found in hard disks that use the form factor, and common applications:
Form
Factor |
Profile |
Platter
Size (in) |
Width
(in) |
Depth
(in) |
Height
(in) |
Application |
5.25" |
Full-Height |
5.12 |
5.75 |
8.0 |
3.25 |
All drives in early 1980s;
Large capacity drives with many platters as late as the mid-1990s |
Half-Height |
5.12 |
5.75 |
8.0 |
1.63 |
Early 1980s through early
1990s |
Low-Profile |
5.12 |
5.75 |
8.0 |
1.0 |
Quantum Bigfoot, mid-to-late
1990s |
Ultra-Low-Profile |
5.12 |
5.75 |
8.0 |
0.75 - 0.80 |
Quantum Bigfoot, mid-to-late
1990s |
3.5" |
Half-Height |
2.5, 3.0, 3.74 |
4.0 |
5.75 |
1.63 |
High-end, high-capacity
drives |
Low-Profile |
2.5, 3.0, 3.74 |
4.0 |
5.75 |
1.0 |
Industry standard, most common
form factor for PC hard disks |
2.5" |
19 mm
Height |
2.5 |
2.75 |
3.94 |
0.75 |
Highest-capacity 2.5"
drives, used in full-featured laptop systems |
17 mm
Height |
2.5 |
2.75 |
3.94 |
0.67 |
Mid-range capacity drives
used in some laptop systems |
12.5 mm
Height |
2.5 |
2.75 |
3.94 |
0.49 |
Low-capacity drives used in
small laptops (subnotebooks) |
9.5 mm
Height |
2.5 |
2.75 |
3.94 |
0.37 |
Lowest-capacity drives used in
very small laptops (mini-subnotebooks) |
PC Card |
Type I |
1.8 |
2.13 |
3.37 |
0.13 |
Not used for hard disks
(yet?) |
Type II |
1.8 |
2.13 |
3.37 |
0.20 |
Smaller-capacity expansion
hard disks for laptops and consumer electronics |
Type III |
1.8 |
2.13 |
3.37 |
0.41 |
Higher-capacity expansion hard
disks for laptops |
Compact
Flash |
Type I |
1.0 |
1.69 |
1.42 |
0.13 |
Smaller-capacity flash cards
for digital cameras, hand-held computers and consumer electronics; not used for hard
disks (yet) |
Type II |
1.0 |
1.69 |
1.42 |
0.20 |
Larger-capacity flash cards
and hard disks for digital cameras, hand-held computers and consumer electronics |
 Next: External Hard Disks
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