Whether you can use an iMac as a monitor depends on its model and year. iMacs from 2009 to mid-2014 work as external displays through Apple’s built in Target Display Mode. Newer Intel iMacs and Apple Silicon models (M1, M3 and M4) require third party software like Luna Display, because Apple removed the feature after 2014. This guide covers all three methods, with the exact models, cables and steps for each.
Can you use an iMac as a monitor?
Yes, you can use an iMac as a monitor through 3 methods and the right one depends entirely on your iMac’s year. Target Display Mode is built into iMacs from 2009 to mid-2014 and needs no extra software. Luna Display is a dongle plus-software solution for 2015 and newer iMacs, including Apple Silicon. A display board hardware mod converts a dead or retired 5K iMac into a standalone monitor.
The key limitation is the hardware itself. iMacs from 2015 onward and every Apple Silicon iMac, cannot accept a direct video input. These models only function as a display through Luna Display’s screen streaming software, not through a plug-in cable.
Which iMac models support Target Display Mode?
Target Display Mode is limited to iMacs released between 2009 and mid-2014. The connection type differs by year and the feature disappeared completely from 2015 onward.
Target Display Mode also caps resolution at 2560×1440 and both computers must run compatible software. The iMac on macOS High Sierra (10.13) or earlier and the source Mac on Catalina or earlier. A Retina 5K iMac cannot enter the mode even if its macOS is downgraded.
How to use an iMac as a monitor with Target Display Mode
Use Target Display Mode in 4 steps, if your iMac is a 2009–2014 model. This is the only method that needs no extra software or hardware.
Confirm compatibility. Check that the iMac is a 2009–mid-2014 model running macOS High Sierra or earlier. Confirm your source computer has a Mini DisplayPort (for 2009–2010 iMacs) or a native Thunderbolt port (for 2011–2014 iMacs).
Connect the cable. Plug a Mini DisplayPort or Thunderbolt cable between the iMac and the source computer.
Activate the mode. Power on both computers, then press Command + F2 (or Command + Fn + F2) on the iMac’s keyboard. The source computer’s screen appears on the iMac.
Exit when finished. Press Command + F2 again or disconnect the cable to return the iMac to normal use.
A Windows PC can drive a 2009–2010 27-inch iMac through Mini DisplayPort. The 2011–2014 iMacs, however, need a source with native Thunderbolt, which most PCs do not have. Check your PC’s ports before buying a cable.
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How to use a 2015 or newer iMac as a monitor with Luna Display
Luna Display turns a newer iMac into a 5K external display in 4 steps. It is the most reliable option for 2015 and later models including Apple Silicon iMacs.
Get the USB-C Luna Display dongle priced at about $120 from Astropad.
Plug the dongle into a Thunderbolt or DisplayPort-capable USB-C port on your primary Mac or PC.
Install the apps — Luna Primary on the source computer and Luna Secondary on the iMac.
Connect both devices to the same network or a cable. The iMac is detected as a display. Enable Retina resolution for a sharp 5K picture.
Luna Display drives the full 5K panel and works with both Mac and Windows sources. It carries three limits worth noting: the iMac must still boot macOS, a wired connection performs more smoothly than Wi-Fi. And it is not recommended for gaming or video because high-motion content can briefly pixelate before it sharpens.
Can you use an M1, M3, or M4 iMac as a monitor?
No, you cannot use an Apple Silicon iMac as a monitor through a cable. Apple removed Target Display Mode after 2014 and M1, M3 and M4 iMacs have no video input port. The only way to use one as a second display is Luna Display’s software. Which streams the screen across a network rather than feeding a true video signal. This method works but it inherits the same high motion limitation and requires the iMac to remain a functioning computer.
Other ways to reuse an iMac’s screen
A retired 27-inch Retina 5K iMac (2014–2020) can be converted into a standalone monitor with a replacement display-driver board costing roughly $190 in parts. The 5K panel inside these iMacs is the same one Apple uses in its Studio Display. So the converted result is a genuine high resolution external monitor. This is an advanced DIY project that fully dismantles the machine. So it suits dead iMacs rather than working ones. The internal components removed during the conversion can often be resold to offset the cost.
Should you use an old iMac as a monitor or sell it?
Reusing an iMac as a monitor makes the most sense for 2009–2014 models you already own, because Target Display Mode is free and built in. For 2015 and newer iMacs the cost of Luna Display ($120 or more) plus its performance limits often makes selling the better value choice. A working iMac still holds real resale value. You can sell your iMac for cash and put the money toward a dedicated 5K monitor, which delivers smoother, lag-free performance than any reuse method.
Why We Recommend Luna Display for Your Setup?
Luna Display is a tiny, powerful device that you can use to turn your iMac into a monitor with ease, even in 2026. It is developed by Astropad, known for professional-grade creative tools used by illustrators and designers. It’s designed in a way to deliver a smooth, high-resolution user experience.
Here’s why we recommend it for your setup:
- It’s a plug-and-play solution that works flawlessly with both Mac and PC.
- You can have crisp 5K resolution and smooth performance over USB-C, Wi-Fi, or even Ethernet.
- What makes it stand out is its broad compatibility, supporting iMacs as far back as 2011.
- While it’s a paid tool, the reliability and visual quality you get far outweigh the limitations of outdated options.
- Ideal for anyone wanting a modern, plug-and-play display experience without tech headaches.
Beyond iMacs, Luna Display allows you to use iPads and MacBooks as external monitors, too. It’s a versatile option for creatives, developers, and multitaskers who want more screen real estate without buying another display.
What Makes the Target Display Mode Outdated to Use in 2026?
Back in the early 2010s, this mode was Apple’s way of letting users repurpose certain iMacs as external monitors. While useful then, it’s now largely obsolete. It only works with mid-2014 or older models, relies on the outdated Thunderbolt 2 port, and caps out at a resolution of 2560×1440. For modern Macs and PCs, it simply doesn’t cut it. If you’re aiming for a smooth, high-res display setup today, there are much better solutions available.
You can read Apple’s official details about Target Display Mode for technical limitations.
Which Devices and Cables Are Required to Use iMac as Monitor?
You’ll need a few key pieces in the first place to use your iMac as a monitor in 2026. Take a look at them:
- First, make sure your iMac is from 2011 or newer and running macOS 10.13 or later (10.15+ recommended for USB connections).
- You also need a primary computer for this purpose; it doesn’t matter whether it’s a Mac or a Windows PC.
- A Luna Display plus the right cable, depending on your model.
If you’re not sure which port your Mac supports, refer to Apple’s Thunderbolt and USB-C guide.
iMac Monitor Not Working? Try These Quick Fixes
Do you face problems while setting up your iMac as a second screen? Don’t worry, it’s usually easier to fix such hiccups.
If your USB port isn’t being detected, try switching to another compatible port or restarting your device.
Ethernet not syncing? Check both ends of the cable and ensure you’re on the same network.
If the Luna app won’t launch or connect, a quick reinstall or update usually solves it. You can also reset the Luna software or reconnect devices to refresh the setup.
Still stuck and wondering how to turn on an iMac desktop display mode? Just press the power button as normal; once powered on, Luna will automatically recognize it when the Secondary app launches. Luna’s support can help.
Make the Most of Your Mac Setup—Starting Today!
The use of an iMac as display in 2026 is a smart, budget-friendly way to upgrade your setup. With Luna Display, it’s a simple and smooth, future-proof solution offering crystal clear visuals and broad compatibility. So, don’t waste your time and turn your iMac into a powerful second monitor today and level up your Apple setup! Want to compare USB-C cables for display or charging performance? Try this Wirecutter USB-C cable guide for top-rated choices.
Frequently Asked Questions
1. Can I use my iMac as a monitor for a Windows PC in 2026?
Yes, you can! Tools like Luna Display support both Mac and Windows PCs. Just make sure your iMac is compatible (generally 2011 or newer) and install the Luna Secondary app on your iMac.
2. Is Luna Display worth it for using an iMac as a monitor?
Absolutely. While it’s a paid device, Luna Display offers 5K resolution, broad compatibility, and works via USB-C, Ethernet, or Wi-Fi. It’s plug-and-play and more reliable than outdated options like Target Display Mode. Luna supports models that 2011 or above if you have old iMac and want to sell old iMac then you can go We Buy Back Electronics and trade in or sale and get instant cash.
3. Why doesn’t Target Display Mode work on my iMac anymore?
Apple discontinued Target Display Mode after mid-2014 iMacs. It only works with older macOS versions (High Sierra or earlier) and outdated Thunderbolt 2 or Mini DisplayPort connections. Most latest devices aren’t compatible anymore.
4. What’s the cheapest way to use an iMac as a second screen?
If your budget is tight, try Duet Display, it’s a low-cost app that works with iPads, Macs, and even PCs. Keep in mind it doesn’t support 5K resolution like Luna does.
5. Can I wirelessly connect my iMac as a monitor?
Yes. With Luna Display and a stable Wi-Fi or Ethernet connection, you can use your iMac wirelessly as a second monitor. Just note that wired connections offer smoother performance, especially for high-res or graphic-heavy use.
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