"How to find which hard drive fits my laptop" is a question we get asked a lot here at PC Advisor. Unfortunately there isn't an industry standard one size fits all internal hard drive size, so the answer is a little long-winded. See Group test: what's the best laptop?

This is because all laptops are designed differently. The size constraints of a desktop-replacement laptop will be different to the dimensions within which an Ultrabookhard drive would have to work, for instance. (Where using the phrase ‘Hard drive’ to refer to both solid-state- and spinning hard disk storage devices.) Take a look at Group test: what's the best portable hard drive? too.

The result of all of this is that the average person wouldn’t automatically know the dimensions of their laptop's hard drive. And knowing the size is imperative if you want to replace your laptop’s storage device. See also How to replace your laptop hard drive.

How to find which hard drive fits your laptop

The first thing that we'd recommend you do is a quick Google search for your laptop's hard drive. Something along the lines of "Macbook Pro hard drive replacement" . If you're lucky you will be able to go to a website that is selling replacement hard drives for your PC, so you can look up the dimensions under the technical specification section.

We were able to find out that the Macbook Pro needs an internal hard drive that fits the dimensions 70 x 100 x 9.5mm, and has a SATA connector. With that information we can now shop around for the best priced hard drive that fits the dimensions and connection type needed.

However, not all laptops hard drive dimensions are as easy to find as the Apple Macbook Pro. For others you will need to perform a web search for the model number (often found on the underside of a laptop). But if you cannot find your laptop’s hard drive size using the internet, you will need to do it the old fashion way - by taking it out and measuring it manually.

Be warned, this is a fiddly job and a small screwdriver set will be very useful when unscrewing the casing and also prying free your laptop's hard drive. If you're not confident with your way around your laptop, consult the manual and it will tell you where to find your hard drive and how to access it. If you're lucky it may even tell you the hard drive's size.

It's worth bearing in mind that a lot of laptops use the same types of hard drives, so if you're Google search points you to a reputable website and you see a hard drive that's stated to work with your laptop, you can be pretty confident it will fit (and remember that you can return unused any item you buy unseen with no penalty).

Hard drive connections

Once you have found which hard drive physically fits into your laptop, there is one critical thing that you should check and that's what connection type your laptop is compatible with.

There are two types of hard drive data connectors for laptops, these are SATA and PATA. If your laptop was manufactured in the past six-years then it will almost certainly have a SATA connection as this has become the industry standard.

If your laptop is a real dinosaur and was made before 2003, then it outdates the invention of SATA and may have a PATA connection.

In either case, it's worth a quick look on the hard drive itself for the SATA or PATA labels, and looking at the connection ports themselves - a quick Google image search for "SATA and PATA connections" will highlight the difference in appearance of the two connector types.

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