An iMac’s screen usually outlives the computer behind it. Two ways can turn it into a display for a newer Mac: Apple’s Target Display Mode on the oldest models, and Second Display on the iMacs that came after. Which one applies depends on the year of your iMac, so start there.
Find your iMac’s year
On the iMac, choose Apple menu › About This Mac. The model and year are shown under the name, for example “iMac (Retina 5K, 27-inch, 2017)”. Then find that year below.
What works on which iMac
| iMac | Target Display Mode | Second Display |
|---|---|---|
| 24‑inch and 27‑inch, 2009 and 2010 | Yes, with a Mini DisplayPort cable | No: it can’t run macOS 12.3 |
| 2011 to mid 2014 | Yes, with a Thunderbolt cable | No: it can’t run macOS 12.3 |
| Retina 5K, late 2014 and mid 2015 | No | No: it can’t run macOS 12.3 |
| Late 2015: 21.5‑inch, Retina 4K and Retina 5K | No | Yes |
| 2017 to 2020, and iMac Pro | No | Yes, over Thunderbolt 3 |
| 24‑inch with Apple silicon | No | Yes, over Thunderbolt |
2009 to mid 2014: Target Display Mode
These iMacs have Apple’s own Target Display Mode, with conditions on both sides. The iMac needs macOS High Sierra 10.13.6 or earlier. The other Mac must be from 2019 or earlier, with macOS Catalina 10.15.8 or earlier, so a Mac with Apple silicon can’t use it. The 2009 and 2010 models connect with a Mini DisplayPort cable, the 2011 to mid 2014 models with a Thunderbolt or Thunderbolt 2 cable. Apple: Use iMac as a display with target display mode
These models can’t run macOS 12.3, so Second Display doesn’t work on them.
Late 2014 and mid 2015 Retina 5K: neither
These two 27‑inch models have no Target Display Mode, and they can’t run macOS 12.3, which Second Display needs. We’d rather say so than sell you an app that won’t start.
Late 2015 and later: Second Display
Every iMac from late 2015 on can run macOS 12.3 Monterey or later, and that is all the display side of Second Display needs: no account and no Screen Recording permission. The Mac you work on needs macOS 14 Sonoma or later. What you need
- Late 2015 models have Thunderbolt 2 ports. Apple’s Thunderbolt 3 (USB‑C) to Thunderbolt 2 Adapter and a Thunderbolt 2 cable connect them to a newer Mac. We haven’t tested that connection yet.
- The 2017 to 2020 models and the iMac Pro connect with a Thunderbolt 3 cable, in a port with the ⚡︎ symbol on each Mac.
- Without a Thunderbolt connection, Wi‑Fi and Ethernet work too, with a compressed picture. Use Wi‑Fi or Ethernet
What to expect from an older iMac
At Highest quality, over a Thunderbolt cable, the picture isn’t compressed on any Mac. We measured 60 frames per second on an iMac 24‑inch with M1; we haven’t measured yet how smoothly older and Intel iMacs show the lossless picture. The speed test recommends the quality your two Macs can keep up, and Check Smoothness shows what you actually get. The statistics line
Over Wi‑Fi, Ethernet or USB the picture is compressed with HEVC. Macs without a hardware HEVC decoder, roughly Intel Macs from before 2017, get H.264, which is limited to 4K: a larger desktop is scaled once to fit. In Settings › Advanced, Encoder can prefer H.264, which suits older Macs. Older Macs and Intel iMacs
Too old for AirPlay, new enough for Second Display
macOS can show another Mac’s screen on an iMac with AirPlay Receiver, but only from the 2019 iMacs on. An iMac from late 2015 or 2017 is too old to receive AirPlay and new enough for Second Display. AirPlay, Sidecar and Universal Control
Not only iMacs
The display role works on any Mac with macOS 12.3 or later, such as a MacBook Air or MacBook Pro from early 2015 on. Since the Mac you work on needs macOS 14, the older Mac usually becomes the display. Use another Mac as a display
Working on a Mac mini? See an iMac as a monitor for a Mac mini. Coming from Target Display Mode? See an alternative to Target Display Mode. Got a 27‑inch Retina model? See a 27‑inch iMac with Retina 5K as a monitor.