What are all the differences between the "2019" Aluminum iMac models and their "Mid-2017" predecessors?

Please note that all "Mid-2017" and "2019" iMac models have been discontinued. However, this Q&A has been updated subsequently and remains quite useful for anyone buying or selling one of these models on the used market.

Although they look essentially identical with even a detailed inspection, there are significant internal differences between the "Mid-2017" iMac models and the "2019" iMac models.

As documented by EveryMac.com, the "2019" iMac models are the essentially entry-level iMac "Core i3" 3.6 21.5" 4K; mid-range iMac "Core i5" 3.0 21.5" 4K and "Core i7" 3.2 21.5" 4K; and high-end 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.

The "Mid-2017" iMac models include the long held over entry-level iMac "Core i5" 2.3 21.5" and the higher-end iMac "Core i5" 3.0 21.5" (4K) , "Core i5" 3.4 21.5" (4K), "Core i7" 3.6 21.5" (4K), iMac "Core i5" 3.4 27" (5K), "Core i5" 3.5 27" (5K), "Core i5" 3.8 27" (5K), and "Core i7" 4.2 27" (5K).

Photo Credit: Apple, Inc. (21.5" 4K and 27" 5K iMac Models)

Because the important differences are internal and easy to overlook, a detailed comparison can be helpful. A greater understanding of the similarities between the lines can be worthwhile, too.

External Differences

All of the 21.5-Inch and 27-Inch "Mid-2017" and "2019" models use essentially the same all aluminum case design that tapers sharply to a 5 mm edge at the sides of the display and all have an integrated 720p "FaceTime HD" webcam in the upper display bezel, speakers integrated at the bottom edge of the display, and dual integrated microphones.

Although each of these displays have a glass cover with an anti-reflective coating, the displays in most of the "Mid-2017" models and all "2019" 4K and 5K models alike are higher quality that the non-Retina display in the long held over entry-level iMac "Core i5" 2.3 21.5" (Mid-2017).

This held over entry-level "Mid-2017" iMac model has a comparatively low resolution 21.5" 1920x1080 LED-backlit 16:9 widescreen IPS display.

By contrast, all of the 21.5" 4K "Mid-2017" and "2019" iMac models have a higher-quality 21.5" 4096x2304 LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 4K" display and the 27" 5K "Mid-2017" and "2019" iMac models have a 27" LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 5K" display with a gigantic 5120x2880 resolution. Both display sizes support a wide color gamut of "one billion colors" and have a brightness rating of 500 nits.

Connectivity Differences (or Lack Thereof)

Connectivity provided by the "Mid-2017" and "2019" iMac models is identical.

All of these models have two Thunderbolt 3 (USB-C) ports, four USB 3.0 ports, one Gigabit Ethernet port (10/100/1000Base-T), an SDXC-capable SD card slot, a 3.5 mm analog headphone jack, 802.11ac Wi-Fi, and Bluetooth 4.2.

Identification Differences

The "Mid-2017" and "2019" iMac models have different Model Numbers. Specifically, the "Mid-2017" iMac models with 21.5" and 27" displays are model number A1418 and A1419, respectively. The "2019" iMac models with 21.5" and 27" displays, on the other hand, are A2116 and A2115, respectively.

The model numbers for the "Mid-2017" iMac line are shared by many earlier models and model numbers for the "2019" iMac line are shared by subsequent models so these identifiers are less useful for precise identification.

However, these systems can be differentiated by Model Identifier in software and EMC Number externally. Just as the site has done for other Macs for more than two decades, EveryMac.com has carefully hand documented these details for your convenience:

Tapered Edge iMac	Subfamily	Model ID	EMC No.
"Core i5" 2.3 21.5"	Mid-2017	iMac18,1	3068
"Core i5" 3.0 21.5"	Mid-2017, 4K	iMac18,2	3069
"Core i5" 3.4 21.5"	Mid-2017, 4K	iMac18,2	3069
"Core i7" 3.6 21.5"	Mid-2017, 4K	iMac18,2	3069
"Core i5" 3.4 27"	Mid-2017, 5K	iMac18,3	3070
"Core i5" 3.5 27"	Mid-2017, 5K	iMac18,3	3070
"Core i5" 3.8 27"	Mid-2017, 5K	iMac18,3	3070
"Core i7" 4.2 27"	Mid-2017, 5K	iMac18,3	3070
"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 identify these iMac models by their serial numbers.

Internal Differences

Internally, the "2019" iMac models are a substantial upgrade from the "Mid-2017" line.

The "Mid-2017" iMac models use the 7th Gen "Kaby Lake" architecture whereas the "2019" iMac models use more advanced 8th and 9th Gen "Coffee Lake" architectures with faster processors and graphics processors. Many "2019" iMac models use faster memory, too.

The 21.5" models in both lines have RAM that can be upgraded, albeit with great difficulty, whereas the 27" models in both lines offer RAM upgrades via a convenient door on the rear of the system. Storage and processors can be upgraded in all of these models, regardless of display size, but it requires essentially a complete disassembly of the computer.

Comparison Charts

The major differences between the 21.5-Inch "Mid-2017" and "2019" Aluminum iMac models are summarized below. Please refer to the specs page for the model of interest for complete details.

21.5-Inch "Mid-2017" & "2019" iMac Differences

	Mid-2017	4K Mid-2017	4K 2019 (i3)	4K 2019
Introduced:	June 2017	June 2017	Mar 2019	Mar 2019
Discontinued:	Oct 2021	Mar 2019	Apr 2021	Apr 2021
Processor Speed:	2.3 GHz	3.0, 3.4 GHz*	3.6 GHz**	3.0 GHz**
Processor Type:	2 Core i5	4 Core i5*	4 Core i3**	6 Core i5**
Processor Family:	Kaby Lake	Kaby Lake	Coffee Lake	Coffee Lake
Processor Generation:	7th Gen	7th Gen	8th Gen	8th Gen
Processor Mounting:	LGA 1151	LGA 1151	LGA 1151	LGA 1151
RAM Type:	2133 MHz PC4-17000	2400 MHz PC4-19200	2400 MHz PC4-19200	2666 MHz PC4-21300
Standard RAM:	8 GB	8 GB	8 GB	8 GB
Maximum RAM:	16 GB	32 GB	32 GB	32 GB
RAM Slots:	2	2	2	2
RAM Upgrade:	Difficult	Difficult	Difficult	Difficult
Standard Storage:	Hard Drive	Hard Drive Fusion Drive	Hard Drive	Fusion Drive
PCIe SSD Connector:	No†	No/Yes†	No†	Yes
Standard Graphics:	Iris Plus 640	Radeon Pro 555/560	Radeon Pro 555X	Radeon Pro 560X‡
VRAM Type:	Integrated	Dedicated	Dedicated	Dedicated
Display Size:	21.5-Inch	21.5-Inch	21.5-Inch	21.5-Inch
Display Resolution:	1920x1080	4096x2304	4096x2304	4096x2304
Thunderbolt:	Dual (3)	Dual (3)	Dual (3)	Dual (3)
Bluetooth:	4.2	4.2	4.2	4.2
Order Number (US):	MMQA2LL/A	MNDY2LL/A MNE02LL/A	MRT32LL/A	MRT42LL/A
EMC Number:	3068	3069	3195	3195
Model Identifier:	iMac18,1	iMac18,2	iMac19,2	iMac19,2
Original Price (US):	US$1099	US$1299 US$1499	US$1299	US$1499
Original Price (UK):	£1049	£1249 £1449	£1249	£1449
Original Price (CA):	C$1399	C$1729 C$1929	C$1699	C$1949
Original Price (AU):	A$1599	A$1899 A$2199	A$1999	A$2299

* By custom configuration, the iMac "Core i5" 3.0 21.5" (4K) and "Core i5" 3.4 21.5" (4K) could be custom configured with a 3.6 GHz Quad Core "Core i7" processor (I7-7700) for an extra US$300. EveryMac.com has documented this custom configuration as its own model, as well.

** 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. EveryMac.com also has documented this custom configuration as its own model, too.

† If these 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 are configured with a "Fusion" Drive, this connector is onboard and occupied by the SSD.

‡ 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.

27-Inch "Mid-2017" & "2019" iMac Differences

The major differences between the standard 27-Inch "Mid-2017" and "2019" Aluminum iMac models are summarized below. Please refer to the specs page for the model of interest for complete details:

	5K Mid-2017	5K 2019
Processor Speed:	3.4, 3.5, 3.8 GHz*	3.0, 3.1, 3.7 GHz**
Processor Type:	Quad Core i5*	Quad Core i5**
Processor Family:	Kaby Lake	Coffee Lake
Processor Generation:	7th Gen	8th Gen/9th Gen
Processor Mounting:	LGA 1151	LGA 1151
Standard RAM:	8 GB	8 GB
Maximum RAM:	64 GB	128 GB†
RAM Slots:	4	4
RAM Upgrade:	Easy (Door)	Easy (Door)
Standard Storage:	Fusion	Fusion
Standard Graphics:	Radeon Pro 570/575/580	Radeon Pro 570X/575X/580X‡
Dedicated VRAM:	4 GB, 8 GB	4 GB, 8 GB
Display Size:	27-Inch	27-Inch
Display Resolution:	5120x2880	5120x2880
Thunderbolt:	Dual (3)	Dual (3)
Bluetooth:	4.2	4.2
Order Number (US):	MNE92LL/A MNEA2LL/A MNED2LL/A	MRQY2LL/A MRR02LL/A MRR12LL/A
EMC Number:	3070	3194
Model Identifier:	iMac18,3	iMac19,1
Orig. Price (US):	US$1799 US$1999 US$2299	US$1799 US$1999 US$2299
Orig. Price (UK):	£1749 £1949 £2249	£1749 £1949 £2249
Orig. Price (CA):	C$2399 C$2649 C$3079	C$2399 C$2649 C$3079
Orig. Price (AU):	A$2699 A$2999 A$3449	A$2799 A$3099 A$3549

* The iMac "Core i5" 3.5 27" 5K and "Core i5" 3.8 27" 5K additionally could be custom configured with a 4.2 GHz Quad Core "Core i7" processor (I7-7700K) for an extra US$300 or US$200, respectively. EveryMac.com has documented this custom configuration as its own model, as well.

** 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, also.

† Oddly, 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.

‡ 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.

Comparison Summary

Ultimately, the "2019" iMac models are an internal upgrade that provide faster performance and graphics performance than the "Mid-2017" iMac models that came before them. Otherwise, the two lines are quite similar.

Please also see EveryMac.com's Ultimate Mac Comparison feature to dynamically compare any iMac model to any other Mac.

New & Used iMac Purchase Options

There are many places to purchase a used "Mid-2017" or "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.