In short: a laptop takes a 2.5" SATA hard drive of the right height, most often 7 mm. Before buying, check that the laptop has a 2.5" bay (many new models have only an M.2 slot for an SSD), what height it takes, and back up your data. If it is your only laptop and you need speed, move the system to an SSD and use the HDD as a second drive or in an external enclosure.
Step 1. What is in the laptop now
Find out the current drive's model and type (HDD or SSD) - step by step in How to tell HDD or SSD. The model number tells you the height and interface from its specs. If the laptop already has an SSD in an M.2 slot and no 2.5" bay, you cannot fit an internal HDD - in that case, use an external drive.
Step 2. Check height and compatibility
- 7 mm - the standard for most recent laptops and the universal choice: it also fits 9.5 mm bays (with a spacer if needed).
- 9.5 mm - older laptops. Such a drive will not fit a 7 mm bay.
- Interface - SATA. Modern SATA III works with laptops that have a SATA II controller.
More on sizes in HDD form factor: 3.5" or 2.5".
Step 3. HDD or SSD
Honestly: if the laptop is slow to boot and launch apps, an SSD is the most noticeable upgrade. An HDD in a laptop makes sense when:
- you need lots of space for little money (photos, video, archives);
- the laptop is old and you just need to replace a failing drive with a working one;
- the drive goes in as a second drive, replacing the optical drive via an adapter.
A comparison of the two options is in HDD vs SSD.
Step 4. Move your data
There are two ways:
- Clean install. Copy your files to an external drive or the cloud, install the new drive and set up the system from scratch. The most reliable option for an old laptop full of clutter.
- Cloning. Connect the new drive via a USB-to-SATA adapter and copy the old drive in full with cloning software. Drive makers offer free utilities for their own models (for example, Acronis True Image for Western Digital, DiscWizard for Seagate). The new drive must be at least as large as the used space on the old one.
Step 5. Installation
- Turn off the laptop, unplug the charger and, if possible, remove the battery.
- Remove the bay cover or bottom panel (look up instructions for your model on the laptop maker's website).
- Unscrew the caddy from the old drive, fit it to the new one and push the drive fully into the connector.
- After powering on: for a clean install, install the system; for a second drive, create a partition in Disk Management, otherwise it will not appear in File Explorer.
What to do with the old drive
If the old drive is healthy, put it in a 2.5" USB 3.0 enclosure and you have a backup drive. If it is noisy, clicking or SMART shows a growing number of reallocated sectors, do not trust it with important data: signs of wear are covered in How long does a hard drive last.
Which drive to choose
For most laptops, the WD Blue 1 TB 2.5" (7 mm) will do. Other options are in the laptop hard drives section.
