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iMac (Retina 5K, 27-inch, 2020) vs iMac (Retina 5K, 27-inch, Late 2015)

iMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2

Quick look

Quick look: iMac (Retina 5K, 27-inch, 2020) against iMac (Retina 5K, 27-inch, Late 2015)
FigureiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Price£1,7993launch price£1,4494launch price
ChipCore i53.1GHz 6-core 10th-generation IntelCore i53.2GHz quad-core Intel
CPU6-coreCPU4-coreCPU
Memory8GBmemory, base8GBmemory, base
Storage256GBstorage, base1TBstorage, base
Display27-inchdisplay27-inchdisplay
Released4 August 20205Available online; Apple gave no in-store day13 October 20154Released
Security updatesNot available6Security updates16 September 20247Security updates ended
Price
The iMac (Retina 5K, 27-inch, 2020) is £1,799 at launch, per Apple Newsroom (UK); the iMac (Retina 5K, 27-inch, Late 2015) is £1,449 at launch, per Apple Newsroom (UK).

True to scale

iMac (Retina 5K, 27-inch, 2020) · 650 × 516 mm frontiMac (Retina 5K, 27-inch, Late 2015) · 650 × 516 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 (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, Late 2015)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Dimensions516 x 650 x 203 mm516 x 650 x 203 mm
Weight8.92 kg9.54 kg
PortsTwo Thunderbolt 3 (USB-C) ports, four USB-A ports, SDXC card slot (UHS-II), 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 ports822
Thunderbolt versionThunderbolt 3Thunderbolt 2
USB-A ports44
HDMINo HDMI port.9No HDMI port.10
SD card slotYesYes
Headphone jackYesYes
KeyboardMagic KeyboardMagic Keyboard
Touch IDNo Touch ID.9No Touch ID.10

Display

Display: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, Late 2015)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Display size27 in27 in
Resolution5120 x 28805120 x 2880
Display type5K Retina displayRetina 5K display with IPS technology
Brightness500 nitsNot available11
Wide colour (P3)YesYes12
Nano-texture optionYesNot available11

Chip and memory

Chip and memory: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, Late 2015)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Chip3.1GHz 6-core 10th-generation Intel Core i53.2GHz quad-core Intel Core i5
Apple siliconIntel processor, not Apple silicon.13Intel processor, not Apple silicon.14
CPU cores64
GraphicsAMD Radeon Pro 5300 with 4GB of GDDR6 memoryAMD Radeon R9 M380 with 2GB of GDDR5 memory
Chip options3.1GHz 6-core Intel Core i5, 3.3GHz 6-core Intel Core i5, 3.8GHz 8-core Intel Core i7, or 3.6GHz 10-core Intel Core i93.2GHz quad-core Intel Core i5, 3.3GHz quad-core Intel Core i5, or 4.0GHz quad-core Intel Core i7
Memory (base)8GB8GB
Memory (maximum)128GB32GB
Memory options8GB, 16GB, 32GB, 64GB or 128GB8GB, 16GB or 32GB
Memory upgradeable by userYes, as Apple documents15Yes, as Apple documents15
Storage (base)256GB1TB
Storage (maximum)8TB3TB
Storage options256GB, 512GB, 1TB, 2TB, 4TB or 8TB SSD1TB hard drive, 1TB, 2TB or 3TB Fusion Drive, or 256GB, 512GB or 1TB flash storage (SSD)

Connectivity

Connectivity: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, Late 2015)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Wi-Fi802.11ac Wi-Fi802.11ac Wi-Fi
Bluetooth5.04.0
Ethernet10/100/1000BASE-T Gigabit Ethernet (RJ-45); configurable to 10Gb Ethernet10/100/1000BASE-T Gigabit Ethernet (RJ-45)
External displays (base)22

Camera and audio

Camera and audio: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, Late 2015)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Camera1080p FaceTime HD cameraFaceTime HD camera
SpeakersStereo speakersStereo speakers
MicrophonesStudio-quality three-mic array with high signal-to-noise ratio and directional beamformingDual microphones

Platform

Platform: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, Late 2015)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Shipped withNot available16OS X El Capitan17
Newest macOSmacOS Tahoe 2618macOS Monterey19
Model identifieriMac20,1 or iMac20,219iMac17,119
Model year20202015

Benchmarks

Benchmarks: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, Late 2015)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, Late 2015)2
Geekbench 7 (CPU, single-core)1,455201,08120
Geekbench 7 (CPU, multi-core)6,319202,90320

Sources

  1. Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications · Default for iMac (Retina 5K, 27-inch, 2020) · Apple’s figure · read 15 Sep 2026

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  2. Apple Support (UK) — iMac (Retina 5K, 27-inch, Late 2015) - Technical Specifications · Default for iMac (Retina 5K, 27-inch, Late 2015) · Apple’s figure · read 15 Sep 2026

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  3. Apple Newsroom (UK) — 27-inch iMac gets a major update · Apple’s figure · read 15 Sep 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) — 27-inch iMac gets a major update · Apple’s figure · read 22 Sep 2026

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  6. Security updates: no end date published. Checked: endoflife.date. Read 22 Sep 2026

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

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  8. Different Thunderbolt generations. iMac (Retina 5K, 27-inch, 2020): Thunderbolt 3. iMac (Retina 5K, 27-inch, Late 2015): Thunderbolt 2.

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  9. iMac (Retina 5K, 27-inch, 2020): No HDMI port. No Touch ID. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications. Read 9 Oct 2026

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  10. iMac (Retina 5K, 27-inch, Late 2015): No HDMI port. No Touch ID. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, Late 2015) - Technical Specifications. Read 9 Oct 2026

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  11. Not published by Apple. Pages checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, Late 2015) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — Apple Updates iMac Family with Stunning New Retina Displays. Read 9 Oct 2026

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

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  13. iMac (Retina 5K, 27-inch, 2020): Intel processor, not Apple silicon. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications. Read 15 Sep 2026

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  14. iMac (Retina 5K, 27-inch, Late 2015): Intel processor, not Apple silicon. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, Late 2015) - Technical Specifications. Read 15 Sep 2026

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

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  16. Not published by Apple. Pages checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — 27-inch iMac gets a major update. Read 9 Oct 2026

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

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  18. Apple Support (UK) — macOS Tahoe 26 is compatible with these computers · Apple’s figure · read 22 Sep 2026

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

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  20. Geekbench Browser (Primate Labs) · third-party figure · read 11 Oct 2026

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Not published by Apple

iMac (Retina 5K, 27-inch, 2020). Apple doesn’t publish for this Mac: colours, pixel density, refresh rate, 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 5K, 27-inch, 2020) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — 27-inch iMac gets a major update, read 9 Oct 2026.

iMac (Retina 5K, 27-inch, Late 2015). Apple doesn’t publish for this Mac: colours, pixel density, refresh rate, 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 5K, 27-inch, Late 2015) - Technical Specifications; 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 (Retina 5K, 27-inch, 2020)? · Should I upgrade my iMac (Retina 5K, 27-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.