SATA 2.5 basically refers to the size of the hard drive. In other words it refers to the form factor in INCHES.
So a SATA 2.5 has a disk platter that is 2.5 inches in diameter. A SATA 2.5″ hard drive is much smaller in comparison to the SATA 3.5″ hard drive.
Often people confuse that SATA 2.5 refers to the version of the SATA interface. However, that is not the case. SATA 2.5 has nothing to do with the performance or the version of the interface or the drive, it just refers to the physical dimensions of the drive.
It should be noted that SATA SSDs can also be found in 2.5″ size. These are conveniently called SATA 2.5″ SSDs. While 2.5″ SATA SSDs do not obviously have a 2.5″ disk platter like the 2.5″ HDDs do, the form factor remains the same so that they can fit in the available 2.5″ drive bays.
In the following text I will talk in detail about what is SATA 2.5 and also dispel some of the misconceptions you may have regarding SATA size and SATA version.
Form Factors of the Hard Drives
SATA 2.5 basically refers to the physical size or the dimensions of the hard drive itself.
The name 2.5″ comes from the diameter of the disk platters used on the HDDs.
There are essentially three types of form factors for hard drives namely:
I will explain these further in the text below.
So What is SATA 2.5?
SATA 2.5 refers to the physical size or the form factor of the hard drive.
2.5″ SATA drives are also known as laptop drives since they are compact and smaller than their 3.5″ desktop hard drive counterparts.
Now there are two types of SATA 2.5 inch drives:
- SATA 2.5″ Hard Disk Drives (HDD)
- SATA 2.5″ Solid State Drive (SSD)
SATA 2.5″ HDDs
SATA 2.5″ hard disk use the spinning platters and they are most commonly found on laptops. As the name suggests, each disk platter is of 2.5 inch diameter.
Due to their smaller size compared to 3.5″ desktop drives, they are intended for portable devices.
2.5″ HDDs are slow and at best can reach speeds of about 100 MB/s and yet they are found on majority of the laptops out there.
SATA 2.5″ SSDs
SATA 2.5″ SSDs use no mechanical parts. They do not have any spinning disk platters and instead use electronic chips for data storage.
As such, SATA 2.5″ SSDs can reach speeds of upto 550 MB/s if connected to a SATA III port.
2.5″ SSDs are much faster compared to their 2.5″ HDD counterparts.
Why SATA SSDs are Also 2.5″?
If the SATA SSD does NOT have any spinning disks then why does it follow the 2.5″ form factor?
The simple reason for this is so that it can easily fit in the available 2.5″ drive bays already available on your laptop and desktops.
Can You Fit 2.5″ SSDs and HDDs in 3.5″ Drive Bays?
Majority of the desktop cases, particularly old cases, offer only 3.5″ drive bays for the large hard disk drives.
So if you wish to install the smaller SATA 2.5 inch SSDs on your desktop that could put you in a predicament.
Fortunately, to securely install a 2.5″ SATA SSD (or a SATA HDD) in your desktop you can get a 3.5″ – 2.5″ drive bay adapters such as the one shown below:
Other Types of Hard Drive Form Factors
As alluded to earlier, aside from 2.5″ form factor, there are also 3.5″ and M.2 form factors for hard drives.
SATA 3.5″ Desktop Hard Disk Drives
3.5″ Hard Disk Drives, also known as desktop drives, are large and are often found in desktops. 3.5″ form factor gets its name, again, from the diameter of the disk platters inside.
M.2 Form Factor
M.2 is a very special form factor. Drives conforming to M.2 form factor can only fit in the dedicated M.2 slots on your motherboard.
SATA 2.5 Should NOT be Confused With SATA Version
Often people confuse SATA 2.5 as indicating the SATA version of the drive or the motherboard’s SATA port.
However, that is not the case.
SATA interface are labelled as follows:
- SATA I = SATA 1 = SATA 1.5 Gb/s = SATA 1.5 Gbps
- SATA II = SATA 2 = SATA 3 Gb/s = SATA 3 Gbps
- SATA III = SATA 3 = SATA 6 Gb/s = SATA 6 Gbps
The most current SATA version is SATA 3.
Also Read: Do You Need an HDD and SSD Both?
Are 2.5″ and 3.5″ SATA Drives the Same?
While in principle they are the same, as they both use spinning platters for storing data, the difference is in their size.
2.5″ drives, as explained earlier, are much smaller than 3.5″ drives. As such, they are found on portable devices like laptops.
As far as the price and performance goes, the 2.5″ HDDs are slower and costlier as compared to 3.5″ HDDs.
What Does 2.5 Mean in SSD?
2.5 in SSD refers to its physical size or form factor.
SSDs come in two form factors: 2.5 and M.2
Are There 3.5″ SSDs?
Yes, there was a time when 3.5″ SSDs had made their presence in the market a long time ago.
However, they are more or less obsolete now and chances are that you may have never seen or heard of them ever.
The reason obviously being that the market trend leans more towards compact and portable devices and since the inception of M.2 NVMe SSDs and their blazingly fast speeds compared to SATA SSDs, despite their very small form factor, the 3.5″ SSD do not make sense.
TL;DR: What is SATA 2.5? It refers to the physical size of the hard drive. It indicates which drive bay it needs to fit inside your PC.
It does not indicate the speed, performance, quality, or version of the drive.