Apple iMac (21.5-inch, Late 2015) vs Apple iMac 24″ (M4)

Every spec side by side, from each maker's published figures.

Only show differences

Better figure, where one is clearly better

Share comparison

iMac (21.5-inch, Late 2015) compared with iMac 24″ (M4)

	AppleiMac (21.5-inch, Late 2015)	AppleiMac 24″ (M4)
Overview
Released
Released	October 2015	November 2024
Performance
Processor
Processor	Intel Core i5-5250U or Intel Core i5-5575R	Apple M4
CPU cores
CPU cores	2 or 4	8 or 10
Graphics
Graphics	Intel HD Graphics 6000 or Intel Iris Pro Graphics 6200	8-core GPU or 10-core GPU
AI engine (NPU)
AI engine (NPU)	–	38 TOPS
Memory
Memory	8 GB or 16 GB	16 GB, 24 GB or 32 GB (better)
Storage
Storage	256 GB to 2 TB	256 GB to 2 TB
CPU
CPU	1.6 GHz dual-core Core i5 with Turbo Boost up to 2.7 GHz or 2.8 GHz quad-core Core i5 with Turbo Boost up to 3.3 GHz; Geekbench identifies the processors as Core i5-5250U and Core i5-5575R, respectively	8-core CPU with 4 performance cores and 4 efficiency cores (two-port model), or 10-core CPU with 4 performance cores and 6 efficiency cores (four-port models)
GPU
GPU	Intel HD Graphics 6000 in the 1.6 GHz model and Intel Iris Pro Graphics 6200 in the 2.8 GHz model; no discrete graphics option	Hardware-accelerated ray tracing
AI engine
AI engine	–	16-core Neural Engine
Memory bandwidth
Memory bandwidth	–	120GB/s
Memory type
Memory type	8 GB of 1867 MHz LPDDR3 onboard memory, configurable to 16 GB; soldered memory cannot be upgraded after purchase (Expert Reviews and Alphr)	–
Storage type
Storage type	1 TB 5400-rpm hard drive on both models; the 1.6 GHz model can have a 1 TB Fusion Drive or 256 GB SSD, and the 2.8 GHz model can have a 1 TB or 2 TB Fusion Drive or 256 GB SSD. Apple specifies 24 GB of flash for the 1 TB Fusion Drive and 128 GB for the 2 TB Fusion Drive.	SSD
Media engine
Media engine	–	Hardware-accelerated H.264, HEVC, ProRes and ProRes RAW; video decode engine; video encode engine; ProRes encode and decode engine; AV1 decode
Display
Screen size
Screen size	21.5″	24″
Resolution
Resolution	1920 × 1080	4480 × 2520 (better)
Panel
Panel	IPS LCD	IPS LCD
Refresh rate
Refresh rate	–	60 Hz
Brightness
Brightness	–	500 nits
Display type
Display type	21.5-inch LED-backlit display with IPS technology; 1920 × 1080 with support for millions of colours. This is the non-Retina model.	4.5K Retina display; actual diagonal 23.5 inches
Pixel density
Pixel density	–	218 ppi
Display features
Display features	–	1 billion colours; wide colour (P3); True Tone; nano-texture glass option on four-port models
Connections
Ports
Ports	2 × Thunderbolt 2, 4 × USB-A, SD card slot, Ethernet, headphone jack	2 × Thunderbolt 4, headphone jack
Ethernet
Ethernet	1 Gb/s	–
External displays
External displays	Up to 1	Up to 1
Wi-Fi
Wi-Fi	802.11ac	Wi-Fi 6E
Bluetooth
Bluetooth	4.0	5.3
Camera
Camera	FaceTime HD	12MP Center Stage
Back ports
Back ports	Four USB 3 ports, two Thunderbolt 2 ports with Mini DisplayPort output, SDXC card slot, Gigabit Ethernet, headphone and optical digital audio output; Kensington lock slot. HDMI, DVI, VGA and dual-link DVI need separately sold adapters.	2 × Thunderbolt / USB 4 (two-port model) or 4 × Thunderbolt 4 (four-port models), each with Thunderbolt 4 and USB 4 (up to 40Gb/s), USB 3.1 Gen 2 (up to 10Gb/s) and DisplayPort; Gigabit Ethernet on the power adapter, standard on four-port models and optional on the two-port model
External displays
External displays	Built-in display at native resolution alongside one external display up to 3840 × 2160 on the 1.6 GHz model or 4096 × 2304 on the 2.8 GHz model; extended desktop and video mirroring	Two-port model: one at up to 6K 60Hz; four-port models: two at up to 6K 60Hz, or one at up to 8K 60Hz
Camera
Camera	–	12MP Center Stage camera with Desk View; 1080p HD video recording; advanced image signal processor with computational video
Speakers
Speakers	Stereo speakers; supports Apple iPhone headset with microphone	High-fidelity six-speaker system with force-cancelling woofers; wide stereo sound; Spatial Audio with Dolby Atmos
Microphones
Microphones	Dual microphones	Studio-quality three-mic array with high signal-to-noise ratio and directional beamforming
Keyboard and mouse
Keyboard and mouse	Magic Keyboard, Magic Mouse 2 and Lightning to USB cable; optional Magic Trackpad 2	Magic Keyboard (two-port model) or Magic Keyboard with Touch ID (four-port models), and Magic Mouse; Magic Trackpad or Magic Keyboard with Touch ID and Numeric Keypad available instead
Design and power
Type
Type	All-in-one	All-in-one
Weight
Weight	5.68 kg	4.42 kg (better)
Width × depth × height
Width × depth × height	528 × 175 × 450 mm	547 × 147 × 461 mm
Operating system
Operating system	macOS	macOS
Size and weight detail
Size and weight detail	Dimensions include the stand; weight varies by configuration and manufacturing process. A built-in VESA mount version was available, but its listed height in inches conflicts with the metric value and is omitted.	–
Power supply
Power supply	100–240 V AC, 50–60 Hz, single phase	143W external power adapter; power lead (2 m)
Noise
Noise	Apple reports operator-position sound pressure of 11.5 dB at idle and during wireless web, and 12 dB during hard-drive seek, tested on the 1.6 GHz Core i5 with 8 GB memory and 1 TB hard drive	–
Materials
Materials	Recyclable aluminium enclosure; arsenic-free display glass and mercury-free LED backlight; speaker enclosures contain 35 percent post-consumer recycled plastic	100% recycled aluminium in the stand; more than 15% recycled content overall
Colours
Colours	–	Blue, Purple, Pink, Orange, Yellow, Green, Silver
In the box
In the box	iMac, Magic Keyboard, Magic Mouse 2, Lightning to USB cable and power lead; OS X El Capitan at launch. The support sheet's macOS Sierra wording reflects a later software update.	iMac, Magic Keyboard (with Touch ID on four-port models), Magic Mouse, 143W power adapter, power lead (2 m), USB-C Charge Cable, polishing cloth (nano-texture glass only)