I'd like to get a larger hard drive for my laptop.

2.5" drives have had tremendous increases in capacity because they are adding extra platters that make them thicker. These thicker drives will not fit into the standard laptop drive bay.

Searching for a 2.5" hard drive over 500 GB is returning thousands of items. Once you read the fine print, you see that they do not fit into a standard 2.5" laptop bay.

On sites like Newegg and Amazon, I can filter by SATA, IDE, Soild State, 5400 RPM, etc - but how do I filter on thickness?

Is there some industry standard that is used to designate what drives that are standard thickness versus a drive that uses non-industry-standard sizing? Meaning, is there some designation that says, "A is a regular 2.5-inch drive" and "B is a fat 2.5-inch drive"?

My only alternative seems to be reading the specifics for the thousands of hard drives out there to see which ones match the exact dimensions of the regular 2.5" drive that I want to replace.


2.5" hard drives normally come in one of three thicknesses:

  • 12.5 mm - these are the Super-Phat drives that probably only larger laptops (DTRs and workstations) can fit. They usually have three platters instead of two, enabling higher capacity.
  • 9.5 mm - this is the most common size and should fit most laptops without problems.
  • 7 mm - these slim drives are used in thinner laptops (like ultraportables). Most SSDs are also in this size, and usually include a plastic bumper to increase the thickness to 9.5 mm in case the HDD mounting system requires it.
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    There's also 15mm, but these aren't exactly meant to be put into laptops (VelociRaptor and Constellation). – Daniel Beck Jan 10 '13 at 20:25
  • The 15mm thick drives are 'Enterprise' class drives, designed for heavier 24/7 usage. They won't fit into any standard 2.5" enclosures which are for thinner drives, however if you look you'll find a few few enclosures that will accommodate them. You might also want to be careful with how much power the USB port is drawing, and possibly use independent power for these drives. – Elliptical view May 29 '18 at 19:21

In the last few years, 2½-inch drives have had tremendous increases in capacity because they are adding extra platters that make them thicker - and these thicker drives will not fit into the standard laptop drive bay.

True and false.

There are two ways to increase capacity for hard drives. One of them is to increase platters. If you add enough of those then your drive will need to be taller. Some of the largest drives for sale use extra platters and are forced to be taller.

However another way is to increase the density at which signals are written to the platter. A modern higher density platter is not thicker.

Using less (but higher density) platters is also cheaper. This makes it one reason why manufacturers prefer more modern platters over using older technology. A few modern platters are simply cheaper than a lot of older platters.

Another one is that drives which are thicker than normal do not sell all that great.

All of this means that in praxis almost all 2½ drives have the same height (9mm), and that only the current generation extra large drives are taller. (12.5mm).

What you probably want to do is this:

  1. Verify which thickness drives your laptop uses (almost certainly 9mm)
  2. Check the height of the drive you want to buy. (almost certainly that will also turn out to be 9mm).

The only place where problems are likely are in ultra-thin notebooks or PDA, which sometimes use 1.8 inch drives, or if you buy the largest capacity drive around. In which case steps 1 or 2 should yield different numbers.

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  • To prevent down time as much as possible, is there a way to get the HDD size on the Media PC without tearing it open first? – jp2code Jan 10 '13 at 20:31
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    Check which brand/model it is, then look at that one up at the manufacturer? (e.g. using dmesg, hdparm or the windows versions of those.) --- Sidenote: Your link leads to a box with a 5400 RPM drive. That is might be done because 5400 RPM usually produce less heat than higher RPM drives. You probably want to replace it with a 5400 RPM drive. – Hennes Jan 10 '13 at 20:39

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