What are all the differences between the "2019" Aluminum iMac models? Which one should I buy?

Please note that all "2019" iMac models have been discontinued and replaced by later models. However, this Q&A has been updated subsequently and can be quite helpful to anyone buying or selling one of these systems whether new or used.

There are two basic "2019" Aluminum iMac designs with 21.5" and 27" displays, respectively. More precisely, the "2019" 21.5-Inch iMac models are the iMac "Core i3" 3.6 21.5" 4K, "Core i5" 3.0 21.5" 4K, and "Core i7" 3.2 21.5" 4K, whereas the "2019" 27-Inch iMac models are the iMac "Core i5" 3.0 27" 5K, "Core i5" 3.1 27" 5K, "Core i5" 3.7 27" 5K, and "Core i9" 3.6 27" 5K.

It is worth noting that these iMac models were introduced in March 2019. In recent years, Apple likely would have formally called them the "Early 2019" series. However, Apple refers to them simply as the "2019" models, a subtle indicator that the company did not plan to introduce additional iMac models until a later year.

With even a quick glance at these iMac models, one could assume that the displays are the primary difference. Although the displays are a notable difference, there are internal differences that perhaps are at least equally important, if not more so.

Accordingly, a detailed comparison can be particularly useful to help determine which "2019" iMac is ideal for your needs.

Photo Credit: Apple, Inc. (2019 iMac Models)

External Differences

Each "2019" iMac model, regardless of display size, uses an all aluminum case that tapers sharply to a 5 mm edge at the sides of the display. By default, none are VESA compliant, but all can be configured with a VESA mount option instead of the aluminum stand at the time of purchase for an extra US$40.

All "2019" iMac models have a fully laminated glass cover over the display and an anti-reflective coating as well as a brightness rating of 500 nits, but the dimensions and resolutions are different, as you would expect.

Specifically, the 21.5-Inch 4K models have a 21.5" 4096x2304 LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 4K" display that runs "pixel doubled" to look like 2048x1152 at twice the density. The 27-Inch "5K" models have a 27" 5120x2880 LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 5K" display that looks like 2560x1440 at twice the density.

All "2019" iMac models also have an integrated 720p "FaceTime HD" webcam embedded in the upper display bezel, speakers integrated at the bottom edge of the display, and dual integrated microphones.

By default, each "2019" iMac model ships with a compact aluminum Apple Magic Keyboard and the multi-touch "Magic Mouse 2". For an additional US$30, you can upgrade from the default keyboard to the "Magic Keyboard with Numeric Keypad" and for an additional US$50, you also can upgrade from the Magic Mouse 2 to the "Magic Trackpad 2," which provides multi-touch and pressure-sensitive "Force Touch" capabilities.

Connectivity Differences (or Lack Thereof)

Connectivity is identical for all of the "2019" iMac models.

All "2019" iMac systems -- regardless of display size -- have an SDXC-capable SD card slot, four USB 3.0 ports, two Thunderbolt 3 (USB-C) ports, one Gigabit Ethernet port (10/100/1000Base-T), and one 3.5 mm headphone jack.

The "2019" iMac series also supports 802.11ac Wi-Fi, which is backwards compatible with the slower 802.11a/b/g/n standards, as well as Bluetooth 4.2.

Using a Thunderbolt 3 port, all "2019" iMac models support one 5120x2880 (5K) external display at 60 Hz with support for one billion colors; two 3840x2160 (4K UHD) external displays at 60 Hz with support for one billion colors; or two 4096x2304 (4K) external displays at 60 Hz with support for millions of colors.

Identification Differences

At the time it was introduced, the "2019" iMac line has unique model numbers that are not the same as earlier "Tapered Edge" Aluminum iMac models. Specifically, the "2019" 21.5-Inch systems are model number A2116 and the 27-Inch systems are model number A2115.

When they first were released, these identifiers were sufficiently unique for most purposes, like upgrading the RAM or storage, but subsequent iMac models share these model numbers, so other identifiers are better for more specific identification.

In software, the Model Identifier is sufficiently unique for just about all purposes. Externally, the EMC number is best as it is not shared by future models using the same case type, although it is inconveniently located on the underside of the stand.

These identifiers for the "2019" iMac models are as follows:

Tapered Edge iMac	Subfamily	Model ID	EMC No.
"Core i3" 3.6 21.5"	2019, 4K	iMac19,2	3195
"Core i5" 3.0 21.5"	2019, 4K	iMac19,2	3195
"Core i7" 3.2 21.5"	2019, 4K	iMac19,2	3195
"Core i5" 3.0 27"	2019, 5K	iMac19,1	3194
"Core i5" 3.1 27"	2019, 5K	iMac19,1	3194
"Core i5" 3.7 27"	2019, 5K	iMac19,1	3194
"Core i9" 3.6 27"	2019, 5K	iMac19,1	3194

Additionally, EveryMac.com's Ultimate Mac Lookup feature also can uniquely identify each of the "2019" iMac models by their serial numbers.

Internal Differences

In addition to the obvious display differences, there are many important internal differences between the "2019" iMac models including processors from different generations, different RAM speeds, different graphics capabilities, differing storage options, and more.

For example, all "2019" 21.5-Inch iMac 4K models use "8th Generation" Intel processors, but the entry-level "2019" iMac 4K model -- the iMac "Core i3" 3.6 21.5" -- uses a slower "Core i3" quad core processor, 2400 MHz DDR4 memory, Radeon Pro 555X graphics with 2 GB of dedicated GDDR5 memory, and an almost amusingly slow 5400 RPM 1 TB hard drive by default. The higher-end iMac 21.5-Inch 4K models, on the other hand, use faster six core "Core i5" or "Core i7" processors, faster 2666 MHz DDR4 memory, Radeon Pro 560X graphics with 4 GB of dedicated GDDR5 memory, and a 1 TB "Fusion" Drive. Thankfully, on August 4, 2020, Apple finally upgraded the default storage in these models to SSDs.

The two entry-level "2019" 27-Inch iMac 5K models -- the iMac "Core i5" 3.0 27" 5K and iMac "Core i5" 3.1 27" 5K -- also have "8th Generation" Intel processors with six cores and 2666 MHz DDR4 memory, but faster Radeon Pro 570X and 575X graphics processors (still with 4 GB of dedicated GDDR5 memory), and a 1 TB "Fusion" Drive.

Finally, the top-of-the line "2019" 27-Inch iMac 5K models -- the stock iMac "Core i5" 3.7 27" 5K and custom configured iMac "Core i9" 3.6 27" 5K -- use newer "9th Generation" Intel processors with six or eight cores, 2666 MHz DDR4 memory, Radeon Pro 580X with 8 GB of dedicated GDDR5 memory, and a 2 TB "Fusion" drive by default.

Apple officially reports that the RAM in the "2019" 21.5-Inch 4K models is "built into the computer" and "it can only be upgraded by an Apple Authorized Service Provider if you choose to upgrade at a later date." This isn't exactly true, because the memory is installed in two SO-DIMM slots, but as first confirmed by site sponsor OWC, accessing these slots requires an enormous effort that involves prying off the glued on display and disassembling the computer. It really is an absurdly complicated design.

The 27-Inch models, by contrast, have a small "pop off" door on the rear that make accessing the RAM quick and easy. The 27-Inch models have four RAM slots instead of two, so they can support more memory, as well.

It is a hassle to upgrade the storage in any of these models, but it also is worth noting that the 27-Inch models, all of which are configured with a hard drive and an SSD merged as a "Fusion" Drive by default, have a SATA III (6 Gb/s) connector for a 2.5" hard drive or SSD as well as a PCIe connector for a small "blade" SSD. If the 21.5-Inch models are not configured with a "Fusion" Drive at the time of purchase, the PCIe connector for the SSD is not onboard and a second drive cannot be installed later.

"2019" iMac Comparison Chart

The major differences between the entry-level Core i3-powered 21.5" 4K iMac, mid-level 21.5" 4K iMac, and 27" 5K iMac models -- size, displays, processors, graphics, upgrades and more -- are summarized below:

	4K 21.5" (i3)	4K 21.5"	5K 27"
Std. Processor Speeds:	3.6 GHz*	3.0 GHz*	3.0, 3.1, 3.7 GHz**
Std. Processor Type:	Core i3*	Core i5*	Core i5**
Std. Processor Cores:	4	6	6
Turbo Boost:	None	4.1 GHz*	4.1, 4.3, 4.6 GHz **
Std. Storage:	Hard Drive♦	Fusion Drive♦	Fusion Drive
SSD Connector:	No†	Yes†	Yes
Std. RAM:	8 GB	8 GB	8 GB
Max. RAM:	32 GB	32 GB	128 GB††
RAM Type (DDR4):	2400 MHz	2666 MHz	2666 MHz
RAM Upgrade:	Difficult	Difficult	Easy (Door)
Video System:	Radeon Pro 555X	Radeon Pro 560X‡	Radeon Pro 570X/575X/580X‡
Video Type:	GDDR5	GDDR5	GDDR5
Video Memory:	2 GB	4 GB	4, 8 GB
Display Size:	21.5-Inch	21.5-Inch	27-Inch
Native Resolution:	4096x2304	4096x2304	5120x2880
Apple Order No (US):	MRT32LL/A	MRT42LL/A	MRQY2LL/A MRR02LL/A MRR12LL/A
Apple Model ID:	iMac19,2	iMac19,2	iMac19,1
EMC Number:	3195	3195	3194
Original Price (US):	US$1299	US$1499	US$1799 US$1999 US$2299
Original Price (CA):	C$1699	C$1949	C$2399 C$2649 C$3079
Original Price (UK):	£1249	£1449	£1749 £1949 £2249
Original Price (AU):	A$1999	A$2299	A$2799 A$3099 A$3549

* By custom configuration, the iMac "Core i3" 3.6 21.5" 4K and "Core i5" 3.0 21.5" 4K could be equipped with a six core 3.2 GHz Core i7 (I7-8700) processor for an extra US$300 or US$200, respectively. It has a Turbo Boost of 4.6 GHz. EveryMac.com also has documented this custom configuration as its own model.

** The iMac "Core i5" 3.1 27" 5K and "Core i5" 3.7 27" 5K additionally could be custom configured with a 3.6 GHz Eight Core "Core i9" processor (I9-9900K) for an extra US$500 or US$400, respectively. It has a Turbo Boost of 5.0 GHz. EveryMac.com also has documented this custom configuration as its own model.

♦ On August 4, 2020, Apple upgraded the default storage in these models to 256 GB SSDs.

† If the 21.5-Inch models were not configured with a "Fusion" Drive at the time of purchase, the PCIe connector for the SSD is not onboard and a second drive cannot be installed later. If they were configured with a "Fusion" Drive, this connector is onboard and occupied by the SSD.

†† Curiously, Apple formally allows up to 32 GB of RAM in the iMac "Core i5" 3.0 27" 5K and up to 64 GB of RAM in the other "2019" iMac 5K models, but site sponsor OWC determined that all of these models actually support up to 128 GB of RAM.

‡ By custom configuration, the stock iMac "Core i5" 3.0 21.5" could be equipped with an AMD Radeon Pro Vega 20 with 4 GB of dedicated HBM2 video memory for an extra US$350 and the stock iMac "Core i5" 3.7 27" 5K could be equipped with an AMD Radeon Pro Vega 48 graphics processor with 8 GB of dedicated HBM2 video memory for an extra US$450.

So, which one should I buy?

At the time these models were new, if price was your primary concern, the "2019" 21.5-Inch 4K iMac models were cheaper upfront, but because they are so much more limited and difficult to upgrade, they likely will not provide as many years of service, and EveryMac.com would suggest that a "2019" 27-Inch 5K iMac is a better bet for most users unless you need a physically smaller computer. Of course, now on the used market, prices are lower still, and the 27-Inch models remain more upgradable.

If you do want a 21.5-Inch 4K iMac, ignoring subsequent options, EveryMac.com would suggest that you at least buy the higher-end iMac "Core i5" 3.0 21.5" 4K model instead of the slower entry-level iMac "Core i3" 3.6 21.5" 4K. The higher-end model has a faster processor with Turbo Boost and two more processor cores, faster RAM, faster graphics with twice as much dedicated memory, and originally a "Fusion" Drive (so it is faster now and more upgradable in the future). That's a lot of additional value for an extra US$200 (or 15% of the purchase price). In single core tasks, the higher-end option is 13% faster and in multicore tasks it is 52% faster, so it definitely provided more bang for the buck, too.

Overall, though, the 27-Inch 5K iMac models are a better option, particularly on the used market. They have an incredibly large and beautiful display, fast processors and graphics processors, and easy-to-upgrade RAM.

All three default 27" configurations are solid choices, but the least expensive option, the iMac "Core i5" 3.0 27" 5K, or the high-end default option, the iMac "Core i5" 3.7 27" 5K; are likely to be the best for most users. Although the value proposition may change somewhat on the used market, the middle option, the iMac "Core i5" 3.1 27" 5K, has a processor and graphics processor that are just barely faster than the entry-level model (originally 4%-5% faster for 11% more money), whereas the high-end default option has a significantly faster processor, much faster graphics processor with twice as much dedicated video memory, and twice the storage capacity (and a much larger SSD which results in significantly faster disk performance).

Of course, if you have an ample budget and want maximum single core performance, the top-of-the-line custom configured iMac "Core i9" 3.6 27" 5K originally was the way to go. It is around 7% faster in single core tasks and 42% faster in multicore tasks than the standard high-end iMac "Core i5" 3.7 27" 5K. Of course, because it originally cost 17% more, it made most sense for someone who has software that can take full advantage of multiple processor cores.

New & Used iMac Purchase Options

There are many places to purchase a "2019" iMac. However, buying from a quality company with a solid track record in the Mac market will provide the best experience and save you money and time, too.

In the US, site sponsor Adorama sells new iMac models with free shipping. Other World Computing and JemJem sell used and refurb iMac models at bargain prices with free shipping, as well. Finally, if you need to sell an iMac, A+ BBB-rated Cash for Your Mac will buy your older iMac with an instant quote and prompt payment.

In the UK, site sponsor Hoxton Macs sells used iMac models with a one-year warranty and free next day delivery throughout the UK. Delivery across Europe also is available starting at just £9.99 for two-day delivery to France and Germany.

In Australia, site sponsor Mac City likewise has a variety of used iMac models sold at low prices and available with a free warranty and fast shipping across Australia.