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iMac (21.5-inch, 2017) vs iMac (Retina 4K, 21.5-inch, Late 2015)

iMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2

Quick look

Quick look: iMac (21.5-inch, 2017) against iMac (Retina 4K, 21.5-inch, Late 2015)
FigureiMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2
Price£1,0493launch price£1,1994launch price
ChipCore i52.3GHz dual-core IntelCore i53.1GHz quad-core Intel
CPU2-coreCPU4-coreCPU
Memory8GBmemory, base8GBmemory, base
Storage1TBstorage, base1TBstorage, base
Display21.5-inchdisplay21.5-inchdisplay
Released7 June 20175ReleasedIn Apple Stores; orderable online from 5 June 2017.13 October 20154Released
Security updates15 September 20256Security updates ended16 September 20246Security updates ended
Price
The iMac (21.5-inch, 2017) is £1,049 at launch, per Apple UK Store (archived 23 June 2017); the iMac (Retina 4K, 21.5-inch, Late 2015) is £1,199 at launch, per Apple Newsroom (UK).

True to scale

iMac (21.5-inch, 2017) · 528 × 450 mm frontiMac (Retina 4K, 21.5-inch, Late 2015) · 528 × 450 mm front

Front faces, from Apple’s published dimensions, drawn to one scale and superposed. Corner rounding is our drawing convention, not a measurement.

Specifications

Each figure is from the source marked by its Mac’s name unless it carries its own small number, which links to where that figure was read.

Body

Body: Apple iMac (21.5-inch, 2017) against Apple iMac (Retina 4K, 21.5-inch, Late 2015)
SpecificationiMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2
Dimensions450 x 528 x 175 mm450 x 528 x 175 mm
Weight5.44 kg5.68 kg
PortsTwo Thunderbolt 3 (USB-C) ports, four USB-A ports, SDXC card slot, Gigabit Ethernet (RJ-45), 3.5 mm headphone jackTwo Thunderbolt 2 ports, four USB 3 ports, SDXC card slot, Gigabit Ethernet (RJ-45), 3.5 mm headphone jack
Thunderbolt ports722
Thunderbolt versionThunderbolt 3Thunderbolt 2
USB-A ports44
HDMINo HDMI port.8No HDMI port.9
SD card slotYesYes
Headphone jackYesYes
KeyboardMagic KeyboardMagic Keyboard
Touch IDNo Touch ID.8No Touch ID.9

Display

Display: Apple iMac (21.5-inch, 2017) against Apple iMac (Retina 4K, 21.5-inch, Late 2015)
SpecificationiMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2
Display size21.5 in21.5 in
Resolution1920 x 10804096 x 2304
Display typeLED-backlit displayRetina 4K display with IPS technology
Wide colour (P3)Not available10Yes11

Chip and memory

Chip and memory: Apple iMac (21.5-inch, 2017) against Apple iMac (Retina 4K, 21.5-inch, Late 2015)
SpecificationiMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2
Chip2.3GHz dual-core Intel Core i53.1GHz quad-core Intel Core i5
Apple siliconIntel processor, not Apple silicon.12Intel processor, not Apple silicon.13
CPU cores24
GraphicsIntel Iris Plus Graphics 640Intel Iris Pro Graphics 6200
Chip options2.3GHz dual-core Intel Core i53.1GHz quad-core Intel Core i5 or 3.3GHz quad-core Intel Core i7
Memory (base)8GB8GB
Memory (maximum)16GB16GB
Memory options8GB or 16GB8GB or 16GB
Memory upgradeable by userNo, as Apple documents14No, as Apple documents14
Storage (base)1TB1TB
Storage (maximum)1TB2TB
Storage options1TB hard drive, 1TB Fusion Drive or 256GB SSD1TB hard drive, 1TB or 2TB Fusion Drive, or 256GB or 512GB flash storage (SSD)15

Connectivity

Connectivity: Apple iMac (21.5-inch, 2017) against Apple iMac (Retina 4K, 21.5-inch, Late 2015)
SpecificationiMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2
Wi-Fi802.11ac Wi-Fi802.11ac Wi-Fi
Bluetooth4.24.0
Ethernet10/100/1000BASE-T Gigabit Ethernet (RJ-45)10/100/1000BASE-T Gigabit Ethernet (RJ-45)
External displays (base)21

Camera and audio

Camera and audio: Apple iMac (21.5-inch, 2017) against Apple iMac (Retina 4K, 21.5-inch, Late 2015)
SpecificationiMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2
CameraFaceTime HD cameraFaceTime HD camera
SpeakersStereo speakersStereo speakers
MicrophonesMicrophoneDual microphones

Platform

Platform: Apple iMac (21.5-inch, 2017) against Apple iMac (Retina 4K, 21.5-inch, Late 2015)
SpecificationiMac (21.5-inch, 2017)1iMac (Retina 4K, 21.5-inch, Late 2015)2
Shipped withNot available10OS X El Capitan16
Newest macOSmacOS Ventura17macOS Monterey17
Model identifieriMac18,117iMac16,217
Model year20172015

Sources

  1. Apple Support (UK) — iMac (21.5-inch, 2017) - Technical Specifications · Default for iMac (21.5-inch, 2017) · Apple’s figure · read 15 Sep 2026

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  2. Apple Support (UK) — iMac (Retina 4K, 21.5-inch, Late 2015) - Technical Specification · Default for iMac (Retina 4K, 21.5-inch, Late 2015) · Apple’s figure · read 15 Sep 2026

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  3. Apple UK Store (archived 23 June 2017) — iMac 21.5-inch, 2.3GHz dual-core Core i5, 8GB, 1TB hard drive, £1,049.00 · third-party figure · read 11 Oct 2026

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  4. Apple Newsroom (UK) — Apple Updates iMac Family with Stunning New Retina Displays · Apple’s figure · read 15 Sep 2026

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  5. Apple Newsroom (UK) — iMac receives major update featuring more powerful graphics, faster processors, Thunderbolt 3 and brighter displays · Apple’s figure · read 15 Sep 2026

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  6. endoflife.date — Apple macOS · third-party figure · read 2 Oct 2026

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  7. Different Thunderbolt generations. iMac (21.5-inch, 2017): Thunderbolt 3. iMac (Retina 4K, 21.5-inch, Late 2015): Thunderbolt 2.

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  8. iMac (21.5-inch, 2017): No HDMI port. No Touch ID. Checked: Apple Support (UK) — iMac (21.5-inch, 2017) - Technical Specifications. Read 9 Oct 2026

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  9. iMac (Retina 4K, 21.5-inch, Late 2015): No HDMI port. No Touch ID. Checked: Apple Support (UK) — iMac (Retina 4K, 21.5-inch, Late 2015) - Technical Specification. Read 9 Oct 2026

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  10. Not published by Apple. Pages checked: Apple Support (UK) — iMac (21.5-inch, 2017) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — iMac receives major update featuring more powerful graphics, faster processors, Thunderbolt 3 and brighter displays. Read 9 Oct 2026

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  11. Apple Newsroom (UK) — Apple Updates iMac Family with Stunning New Retina Displays · Apple’s figure · read 3 Oct 2026

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  12. iMac (21.5-inch, 2017): Intel processor, not Apple silicon. Checked: Apple Support (UK) — iMac (21.5-inch, 2017) - Technical Specifications. Read 15 Sep 2026

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  13. iMac (Retina 4K, 21.5-inch, Late 2015): Intel processor, not Apple silicon. Checked: Apple Support (UK) — iMac (Retina 4K, 21.5-inch, Late 2015) - Technical Specification. Read 15 Sep 2026

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  14. Apple Support (UK) — Install memory in an iMac · Apple’s figure · read 18 Oct 2026

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  15. Apple Support (UK) — iMac (Retina 4K, 21.5-inch, Late 2015) - Technical Specification · Apple’s figure · read 11 Oct 2026

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  16. Apple Newsroom (UK) — Apple Updates iMac Family with Stunning New Retina Displays · Apple’s figure · read 9 Oct 2026

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  17. Apple Support (UK) — Identify your iMac model · Apple’s figure · read 15 Sep 2026

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Not published by Apple

iMac (21.5-inch, 2017). Apple doesn’t publish for this Mac: colours, pixel density, brightness, refresh rate, nano-texture option, GPU cores, storage upgradeable by user, maximum continuous power. Geekbench 7: the Mac chart has no entry for this Mac, so no figures are shown (chart read 10 Oct 2026). Pages checked: Apple Support (UK) — iMac (21.5-inch, 2017) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — iMac receives major update featuring more powerful graphics, faster processors, Thunderbolt 3 and brighter displays, read 9 Oct 2026.

iMac (Retina 4K, 21.5-inch, Late 2015). Apple doesn’t publish for this Mac: colours, pixel density, brightness, refresh rate, nano-texture option, GPU cores, storage upgradeable by user, maximum continuous power. Geekbench 7 Metal: the Mac chart has no Metal score for this Mac (chart read 10 Oct 2026). Pages checked: Apple Support (UK) — iMac (Retina 4K, 21.5-inch, Late 2015) - Technical Specification; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — Apple Updates iMac Family with Stunning New Retina Displays, read 9 Oct 2026.

If you own one of them

Whether to move is a different question from which is better. Each Mac has a page on it: what its successor changes (the newest Mac in its line where Apple sells one, otherwise the Mac this site treats as its replacement, which can be in another line), what it fetches and whether it still gets updates. Should I upgrade my iMac (21.5-inch, 2017)? · Should I upgrade my iMac (Retina 4K, 21.5-inch, Late 2015)?

The pairs a buyer of either Mac would also weigh. Any two Macs in the catalogue can be compared from the chooser.