iMac RAM Upgrade: Memory for Every Intel iMac

Most Intel iMacs can take more memory, but how hard it is to reach depends on the model. Every 2009–2011 iMac and every 27-inch from Late 2012 to 2020 has an access door, and we fit 16GB from $329. The 21.5-inch 2012–2013, 2017 and 2019 models need the display and logic board out, so they start from $449, and the 21.5-inch Mid 2014 and Late 2015 (including the Retina 4K) cannot be upgraded at all because the memory is soldered to the board.

Before you spend anything, check that memory is what is holding the iMac back. If it still has a hard drive or Fusion Drive, the drive is usually the bigger problem. You bring the iMac to our workshop near Castle Hill (we do not collect or work on iMacs onsite), and customers come from across the Hills District and Western Sydney. Memory jobs usually take one to two business days when parts are in stock. It is part of our iMac repair and upgrade service.

iMac RAM by model: access, type and real maximums

Apple's official maximums are conservative on several models. Larger kits have since been certified by OWC or confirmed by owners, so the practical ceiling is higher. "Tested max" below means certified by OWC or listed by EveryMac, not promised by Apple.

Notes on the awkward ones:

• 27-inch 5K 2017: Apple's memory page lists 64GB, although the Tech Specs for the 3.4GHz model say 32GB; OWC certified 64GB in every 2017 27-inch, including that one. One owner reports 128GB running stably and another found only 64GB usable, so we treat 64GB as the practical maximum.
• 27-inch 5K 2019: Apple lists 64GB; OWC certifies 128GB as four 32GB modules.
• 27-inch 5K 2020: 128GB (four 32GB modules) is Apple's own official maximum.
• 21.5-inch Mid 2010: OWC's listings conflict, so we treat 16GB as the safe limit. The education-only Late 2011 21.5-inch is supported by Apple to 8GB, and third parties report 16GB.

How the memory is reached

• 2009–2011, both sizes: four slots behind an access door in the bottom of the iMac, held by Phillips screws.
• 27-inch, Late 2012 to 2020: four slots behind a rear door, opened by pressing a small grey button just above the power socket. It takes minutes, which is why fitting memory you have bought yourself costs from $89.
• 21.5-inch 2012–2013, 2017 and 2019: two slots behind the logic board. Apple describes this memory as not removable by users. The glued display comes off, the logic board comes out, and the display goes back on with new adhesive strips.
• 21.5-inch Mid 2014, Late 2015 and Retina 4K Late 2015: soldered to the logic board, so nothing can be done.

How much RAM you need

These are our recommendations from working on these machines, not Apple figures, and most people need less than they expect.

• 8GB: fine for browsing, email and documents a couple of apps at a time. It starts to run short with a browser full of tabs, Microsoft 365 and a video call open together.
• 16GB: the sensible target for most home and office use, including a large Photos library. It is what our standard upgrade fits.
• 32GB: worth it for regular photo editing, music production with plenty of tracks and plug-ins, or several heavy apps open at once.
• 64GB or 128GB: for specific professional work such as long 4K or 5K video timelines, big sample libraries or several virtual machines. If you are not sure you need it, you do not. A 128GB kit for a 2019 or 2020 27-inch is listed at about $1,400 as a part alone at Australian retail.

One catch for creative work: current Adobe Creative Cloud apps need macOS Sonoma or later, which only the 2019 and 2020 iMacs run officially. Adding 64GB to an older iMac will not help if the software will not install. The patcher can take older models further, with caveats; see newer macOS on an old iMac.

Check whether more RAM will help

Open Activity Monitor (Applications > Utilities), click the Memory tab and use the iMac normally for an hour or so.

• Memory Pressure graph mostly green: you have enough memory, and more will not make the iMac faster.
• Yellow or red for long stretches, with Swap Used climbing into gigabytes: the iMac is short of memory and an upgrade will help.
• What is fitted now: About This Mac shows the total, and System Information lists each slot and what is in it, which tells us whether we can add modules or need to replace them.

When RAM will not help

If your iMac still has a hard drive or a Fusion Drive, fix that first. Extra memory lets macOS keep more in hand, but apps, files and the system itself still load from the drive, and on an Intel iMac a spinning disk under current macOS is nearly always the slowest part. An iMac SSD upgrade from $599 does more for a hard-drive iMac than any amount of RAM.

Memory also will not make an older processor quicker, cool an iMac whose fans are clogged with dust, or add macOS versions: Apple sets support by model, not by how much memory is fitted. For the full list of causes and checks, read why your iMac is running slow.

SSD and RAM together on a 21.5-inch

On the 21.5-inch 2012–2013, 2017 and 2019 models, both the drive and the memory are reached by taking off the glued display, so doing them together means one teardown and one set of new adhesive strips instead of two.

• 16GB RAM on its own: from $449
• 16GB RAM added to an SSD upgrade: from $249 extra
• 500GB SSD plus 16GB RAM together: from $848 (two separate jobs start from $1,048)
• 1TB SSD plus 16GB RAM together: from $948 (separately, from $1,148)

That $200 saving is why we suggest deciding on memory when you book the SSD. On a 21.5-inch 4K 2017 worth around $500, or a 4K 2019 at roughly $275–$400, the combined job, from $848, costs more than the iMac would fetch, so it makes sense only if you mean to keep it. Set against the $2,399 a new 24-inch M4 iMac costs, it is about a third of the price for a fast, capable machine. Bear in mind the 2019 runs Sequoia officially, while the 2017 stopped at Ventura, which no longer gets Apple security updates.

Prices

• 27-inch Late 2012 to 2020, and all 2009–2011 models (access door), with 16GB fitted: from $329
• Fitting RAM you supply on an access-door model: from $89
• 21.5-inch 2012–2013, 2017 and 2019 (display removal), with 16GB: from $449, or from $249 extra with an SSD upgrade
• 32GB, 64GB and 128GB kits: quoted by model
• 21.5-inch Mid 2014 and Late 2015: soldered, so there is nothing to sell you

Prices are in AUD, include GST and carry our 12-month warranty on parts and labour. For context, Australian retailers list 16GB kits for access-door iMacs at roughly $263 to $310 for the part alone.

Call 0400 454 859

Worth it or not, by model

The values in brackets are what working units were being advertised for privately on Gumtree in September 2026.

• 27-inch 5K 2019 (around $799) and 2020 (around $999): yes. They are the newest Intel iMacs, on Sequoia and Tahoe respectively, and the rear door keeps the cost down. See 27-inch 5K 2019–2020.
• 27-inch 5K 2014–2017 (2017 around $475, Late 2015 around $400): worth it when memory pressure says so and the drive is already an SSD. See 27-inch 5K 2014–2017.
• 27-inch 2012–2013 (around $220): the upgrade, from $329, costs about one and a half times what the whole machine would sell for, so spend it only if you specifically want to keep this iMac. Do the SSD first, and if you still need memory, supplying modules yourself and paying from $89 to have them fitted saves money only if you can find them for less than $240. See 27-inch 2012–2013.
• 2009–2011 (27-inch 2011 listings: $60–$150): only the fitting option, from $89, makes sense, and only if the iMac already has an SSD and does a job you need. See iMac 2009–2011.
• 21.5-inch 2012–2013, 2017 and 2019: do it with the SSD, from $249 extra, rather than on its own, from $449. See 21.5-inch 2012–2014 and 21.5-inch 2015–2019.
• 21.5-inch Mid 2014 and Late 2015: not possible. An SSD is the upgrade for these.

Questions

Can I upgrade my iMac RAM myself?

On models with an access door, yes. The 2009 to 2011 iMacs have a door in the bottom held by Phillips screws, and 27-inch models from Late 2012 to 2020 have a rear door opened with a small button above the power socket. On 21.5-inch models from 2012 onward, the glued display and logic board have to come out, which is not a job for the kitchen table. If you buy the memory yourself, we fit it on access-door models from $89.

Is 8GB of RAM enough for an iMac?

For light use with one or two apps at a time, 8GB is workable. Many people now run a browser with dozens of tabs, Microsoft 365 and video calls together, and 8GB can run short with that mix. Check the Memory Pressure graph in Activity Monitor during a normal day. If it stays green, 8GB is enough for you. If it is often yellow or red, 16GB is the sensible step.

Does adding RAM make an iMac faster?

Only when the iMac is short of memory. Extra RAM reduces how often macOS has to swap data out to the drive, which helps a lot when memory pressure is high, but it does nothing for a Mac that already has enough. It will not speed up a slow hard drive, an older processor or an overheating machine, and it does not change which macOS versions Apple supports on your model.

What RAM does a 2017 iMac take?

It depends which 2017. The 21.5-inch non-Retina model uses DDR4 at 2133MHz and the 21.5-inch Retina 4K uses DDR4 at 2400MHz, both in two slots behind the logic board. The 27-inch Retina 5K takes DDR4 2400MHz (PC4-19200) in four slots behind the rear door. Check the exact model name in About This Mac before buying modules, because the speed and the way the memory is reached differ.

Can a 27-inch iMac take 128GB of RAM?

The 2019 and 2020 models can. The 2020 27-inch officially supports 128GB as four 32GB modules. Apple lists the 2019 at 64GB, but OWC has tested and sells a 128GB kit for it. Reports for the 2017 27-inch conflict, so we treat 64GB as its practical limit. A 128GB kit costs around $1,400 as a part alone, so make sure your work needs it before buying.

Can you upgrade the RAM in a 2015 21.5-inch iMac?

No. The 21.5-inch Late 2015 and Retina 4K Late 2015 have their memory soldered to the logic board, and Apple lists it as not upgradeable. The 21.5-inch Mid 2014 is the same. Whatever it shipped with, usually 8GB and sometimes 16GB, is what it keeps. An SSD upgrade from $599 is the best improvement for these models and makes far more difference than memory would on a hard-drive machine.

Do I need more RAM to install a newer macOS on an old iMac?

Apple sets macOS support by model, so extra memory does not add versions to the list. If you use the OpenCore Legacy Patcher to go further, it needs more than 3GB of RAM to install macOS Sonoma or Sequoia, which any iMac with 4GB or more already meets. More useful than extra RAM is an SSD, because a newer macOS running from a hard drive is painfully slow.