Apple iMac (Retina 4K, 21.5-inch, Late 2015) vs Apple iMac (Retina 5K, 27-inch, 2019)

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iMac (Retina 4K, 21.5-inch, Late 2015) compared with iMac (Retina 5K, 27-inch, 2019)

	AppleiMac (Retina 4K, 21.5-inch, Late 2015)	AppleiMac (Retina 5K, 27-inch, 2019)
Overview
Released
Released	October 2015	March 2019
Performance
Processor
Processor	Intel Core i5-5675R or Intel Core i7-5775R	Intel Core i5-8500, Intel Core i5-8600, Intel Core i9-9900K or Intel Core i5-9600K
CPU cores
CPU cores	4	6 or 8
CPU threads
CPU threads	–	6 or 16
Graphics
Graphics	Intel Iris Pro Graphics 6200	Radeon Pro 570X (4 GB GDDR5), Radeon Pro 575X (4 GB GDDR5), Radeon Pro 580X (8 GB GDDR5) or Radeon Pro Vega 48 (8 GB HBM2)
Memory
Memory	8 GB or 16 GB	8 GB, 16 GB, 32 GB or 64 GB (better)
Storage
Storage	256 GB to 2 TB	256 GB to 3 TB (better)
CPU
CPU	3.1 GHz quad-core Core i5 with Turbo Boost up to 3.6 GHz; configurable to 3.3 GHz quad-core Core i7 with Turbo Boost up to 3.8 GHz	Six-core Core i5 at 3.0 GHz (Turbo Boost 4.1 GHz), 3.1 GHz (Turbo Boost 4.3 GHz) or 3.7 GHz (Turbo Boost 4.6 GHz); upper two bases configurable to 3.6 GHz eight-core Core i9 with Turbo Boost up to 5.0 GHz. Exact K-suffix CPU identities follow Geekbench’s model database; Macworld instead lists KF suffixes.
GPU
GPU	–	Radeon Pro 570X or 575X with 4 GB GDDR5, or Radeon Pro 580X with 8 GB GDDR5; only the upper base supports Radeon Pro Vega 48 with 8 GB HBM2
Memory type
Memory type	1867 MHz LPDDR3 onboard memory; 8 GB standard, configurable to 16 GB at purchase	2666 MHz DDR4; 8 GB standard as two 4 GB modules in four user-accessible SO-DIMM slots. Lower base configurable to 16/32 GB; upper two bases to 16/32/64 GB.
Storage type
Storage type	1 TB 5400-rpm hard drive; optional 1 TB or 2 TB Fusion Drive, or 256 GB or 512 GB SSD. The 1 TB Fusion Drive combines a hard drive with 24 GB of flash; the 2 TB version has 128 GB of flash.	570X base: 1/2 TB Fusion Drive or 256/512 GB/1 TB SSD. 575X base: 1/2/3 TB Fusion Drive or 256/512 GB/1 TB SSD. 580X/Vega base: 2/3 TB Fusion Drive or 512 GB/1/2 TB SSD.
Display
Screen size
Screen size	21.5″	27″
Resolution
Resolution	4096 × 2304	5120 × 2880 (better)
Panel
Panel	IPS LCD	IPS LCD
Brightness
Brightness	–	500 nits
Display type
Display type	LED-backlit Retina 4K display with IPS technology and support for millions of colours	LED-backlit Retina 5K display; IPS panel confirmed by EveryMac; Apple does not publish native refresh rate in this model’s specification sheet
Display features
Display features	P3 colour gamut; Apple does not publish brightness or refresh rate in this model's specification sheet	Wide colour (P3); supports one billion colours
Connections
Ports
Ports	2 × Thunderbolt 2, 4 × USB-A, SD card slot, Ethernet, headphone jack	2 × Thunderbolt 3, 4 × USB-A, SD card slot, Ethernet, headphone jack
Ethernet
Ethernet	1 Gb/s	1 Gb/s
External displays
External displays	Up to 1	Up to 2 (better)
Wi-Fi
Wi-Fi	802.11ac	802.11ac
Bluetooth
Bluetooth	4.0	4.2
Camera
Camera	FaceTime HD	FaceTime HD
Back ports
Back ports	Four USB 3 ports, two Thunderbolt 2 ports with Mini DisplayPort output, SDXC card slot, Gigabit Ethernet, 3.5 mm headphone and optical digital audio output; Kensington lock slot. HDMI, DVI, VGA and dual-link DVI require separately sold adapters.	Four USB-A ports; two Thunderbolt 3 USB-C ports with DisplayPort, Thunderbolt up to 40 Gb/s and USB 3.1 Gen 2 up to 10 Gb/s; SDXC, Gigabit Ethernet and 3.5 mm headphone jack; Kensington lock slot. Thunderbolt 2, HDMI, DVI and VGA require separately sold adapters.
External displays
External displays	Built-in display at full native resolution alongside one external display up to 4096 × 2304; extended desktop and video mirroring	Built-in display at full native resolution alongside one 5120 × 2880 display at 60 Hz with one billion colours, two 3840 × 2160 displays at 60 Hz with one billion colours, or two 4096 × 2304 displays at 60 Hz with millions of colours
Speakers
Speakers	Stereo speakers; supports Apple iPhone headset with microphone	Stereo speakers
Microphones
Microphones	Dual microphones	Built-in microphone
Keyboard and mouse
Keyboard and mouse	Rechargeable Magic Keyboard and Magic Mouse 2; optional Magic Trackpad 2 with Force Touch	Rechargeable Magic Keyboard and Magic Mouse 2; optional Magic Keyboard with Numeric Keypad and Magic Trackpad 2
Design and power
Type
Type	All-in-one	All-in-one
Weight
Weight	5.68 kg (better)	9.42 kg
Width × depth × height
Width × depth × height	528 × 175 × 450 mm	650 × 203 × 516 mm
Operating system
Operating system	macOS	macOS
Size and weight detail
Size and weight detail	Dimensions include the stand; weight varies by configuration. A built-in VESA mount version was also available.	Dimensions include the stand; weight varies by configuration. A built-in VESA mount version was also available.
Power supply
Power supply	100–240 V AC, 50–60 Hz, single phase	100–240 V AC, 50–60 Hz, single phase
Noise
Noise	Apple's 3.1 GHz Core i5, 8 GB, 1 TB hard-drive test configuration: operator-position sound pressure 11 dB at idle and wireless web, 11.5 dB during hard-drive seek	–
Materials
Materials	Recyclable aluminium enclosure; arsenic-free display glass; mercury-free LED backlight	Recyclable aluminium enclosure; arsenic-free glass and mercury-free LED backlight
In the box
In the box	iMac, Magic Keyboard, Magic Mouse 2, power lead and Lightning to USB cable	iMac, Magic Keyboard, Magic Mouse 2, power lead and Lightning to USB cable