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Hard drive and SSD for iMac: compatibility, year by year
Swapping an old iMac's hard drive for an SSD often gives it five more years of life: it starts up in a few seconds instead of several minutes. But each generation has its own format, and from 2012 onwards you have to detach the screen to reach it. Here, model by model, is what fits.
21.5-inch iMac
| Model | Years | Original storage | What fits |
|---|---|---|---|
| iMac 21.5" (A1311) | Late 2009-2011 | 3.5-inch SATA hard drive | 2.5-inch SATA SSD with an adapter bracket, or 3.5-inch hard drive |
| iMac 21.5" (A1418) | Late 2012-2019 | 2.5-inch SATA hard drive, sometimes Fusion Drive | Any 2.5-inch SATA SSD; on 2013-2017 models that have the PCIe connector, an original Apple SSD as well |
| iMac 21.5" Retina 4K (A1418, A2116) | 2015-2019 | 2.5-inch hard drive, Fusion Drive or SSD only | As above; some models have only the 2.5-inch drive |
| iMac 24" (A2438, A2439 and later) | Since 2021 | SSD soldered to the logic board | Cannot be replaced: use an external SSD |
27-inch iMac
| Model | Years | Original storage | What fits |
|---|---|---|---|
| iMac 27" (A1312) | Late 2009-2011 | 3.5-inch SATA hard drive | 2.5-inch SATA SSD with an adapter bracket, or 3.5-inch hard drive |
| iMac 27" (A1419) | Late 2012-2019 | 3.5-inch SATA hard drive, often Fusion Drive | 3.5-inch drive or 2.5-inch SATA SSD with bracket; on 2013-2017 models that have the PCIe connector, an original Apple SSD as well |
| iMac 27" Retina 5K (A2115) | 2019 | 3.5-inch drive or Fusion Drive | 3.5-inch drive or 2.5-inch SATA SSD with bracket |
| iMac 27" Retina 5K (A2115) | 2020 | SSD soldered to the logic board | Cannot be replaced: use an external SSD |
The model number is engraved under the iMac's stand. As it does not always change from one year to the next, also check the year in Apple menu > About This Mac.
Fusion Drive: what it is
A Fusion Drive combines a small SSD (24 to 128 GB) with a hard drive, which macOS presents as a single disk. When the hard drive ages, the iMac becomes slow again. Replacing the hard drive with a SATA SSD is the most effective repair; you can keep the small SSD as a second disk or replace it with a larger one.
Pitfalls to know about
- 2011 iMac: the temperature sensor. It is built into the original hard drive. With another drive, the fan runs at full speed, unless you use a suitable sensor cable or fan-control software.
- iMac since late 2012: the screen is glued. You have to cut the adhesive and replace it when reassembling. One mistake breaks the panel: this is a repair to do with the right tools.
- 2.5-inch SSD in a 3.5-inch bay: you need an adapter bracket, otherwise the SSD rattles around in the bay.
- Before the change: back up with Time Machine. Afterwards, format the SSD as APFS and reinstall macOS over the Internet.
What we offer for iMac
- Original Apple SSD for 2013-2017 iMac: 256 GB, 512 GB, 1 TB and 2 TB.
- 2.5-inch SATA SSD: 512 GB, 500 GB and 2 TB.
- Hard drive bracket for 21.5" iMac (A1418/A2116), if the old bracket is broken or lost.
- Full SSD: moving to a bigger drive on a Mac
- Reinstalling macOS over the Internet
- SSD not recognised by your Mac? APFS vs HFS+ explained
- Mac too old for the update: OpenCore or SSD
- Mac serial number: finding the model and year
Frequently asked questions
My iMac is very slow: is it the hard drive?
Very often, yes, especially on a 2012 to 2019 iMac with a hard drive or Fusion Drive. Moving to an SSD is the repair that makes the biggest difference.
Can you change the SSD in a 24-inch iMac?
No. On 24-inch iMacs with an Apple chip, the storage is soldered. To get more space, you need an external SSD.
Can you fit an SSD without opening the iMac?
Yes: you can install macOS on an external USB or Thunderbolt SSD and start up from it. It is slower than an internal SSD, but much faster than an old hard drive.
Should you keep the Fusion Drive?
No. An SSD alone is faster and more reliable. The small SSD from the Fusion Drive can stay as a secondary disk.
