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iMac (Retina 4K, 21.5-inch, Late 2015) vs MacBook Air (11-inch, Early 2015)

iMac (Retina 4K, 21.5-inch, Late 2015)1MacBook Air (11-inch, Early 2015)2

Quick look

Quick look: iMac against MacBook Air
FigureiMac1MacBook Air2
Price£1,1993launch price£7494launch price
ChipCore i53.1GHz quad-core IntelCore i51.6GHz dual-core Intel
CPU4-coreCPU2-coreCPU
Memory8GBmemory, base4GBmemory, base
Storage1TBstorage, base128GBstorage, base
Battery life Not available5No batteryUp to10 hrsvideo playback, claimed
Released13 October 20153Released9 March 20154Released
Security updates16 September 20246Security updates ended16 September 20246Security updates ended
Price
The iMac is £1,199 at launch, per Apple Newsroom (UK); the MacBook Air is £749 at launch, per Apple Newsroom (UK).
Kind of Mac
The iMac is an all-in-one; the MacBook Air is a laptop. The MacBook Air has a battery, whereas the iMac has none.

True to scale

iMac (Retina 4K, 21.5-inch, Late 2015) · 528 × 450 mm frontMacBook Air (11-inch, Early 2015) · 300 × 192 mm footprint

An all-in-one and a laptop are different shapes, so they stand side by side rather than superposed: the front face of one and the footprint of the other, from Apple’s published dimensions, at one scale. 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 4K, 21.5-inch, Late 2015) against Apple MacBook Air (11-inch, Early 2015)
SpecificationiMac1MacBook Air2
Dimensions450 x 528 x 175 mm3–17 x 300 x 192 mm
Weight5.68 kg1.08 kg
PortsTwo Thunderbolt 2 ports, four USB 3 ports, SDXC card slot, Gigabit Ethernet (RJ-45), 3.5 mm headphone jackTwo USB 3 ports (up to 5 Gbps), Thunderbolt 2 port (up to 20 Gbps), MagSafe 2 power port, 3.5 mm headphone jack
Thunderbolt ports21
Thunderbolt versionThunderbolt 2Thunderbolt 2
USB-A ports42
HDMINo HDMI port.7No HDMI port.8
SD card slotYesNo SD card slot.8
Headphone jackYesYes
MagSafeNot available9Yes
KeyboardMagic KeyboardFull-size backlit keyboard
Touch IDNo Touch ID.7No Touch ID.8

Display

Display: Apple iMac (Retina 4K, 21.5-inch, Late 2015) against Apple MacBook Air (11-inch, Early 2015)
SpecificationiMac1MacBook Air2
Display size21.5 in11.6 in
Resolution4096 x 23041366 x 768
Display typeRetina 4K display with IPS technologyLED-backlit glossy widescreen display
Wide colour (P3)Yes10Not available11

Chip and memory

Chip and memory: Apple iMac (Retina 4K, 21.5-inch, Late 2015) against Apple MacBook Air (11-inch, Early 2015)
SpecificationiMac1MacBook Air2
Chip3.1GHz quad-core Intel Core i51.6GHz dual-core Intel Core i5
Apple siliconIntel processor, not Apple silicon.12Intel processor, not Apple silicon.13
CPU cores42
GraphicsIntel Iris Pro Graphics 6200Intel HD Graphics 6000
Chip options3.1GHz quad-core Intel Core i5 or 3.3GHz quad-core Intel Core i71.6GHz dual-core Intel Core i5 or 2.2GHz dual-core Intel Core i7
Memory (base)8GB4GB
Memory (maximum)16GB8GB
Memory options8GB or 16GB4GB or 8GB
Memory upgradeable by userNo, as Apple documents14No, as Apple documents15
Storage (base)1TB128GB
Storage (maximum)2TB512GB
Storage options1TB hard drive, 1TB or 2TB Fusion Drive, or 256GB or 512GB flash storage (SSD)16128GB, 256GB or 512GB

Battery and power

Battery and power: Apple iMac (Retina 4K, 21.5-inch, Late 2015) against Apple MacBook Air (11-inch, Early 2015)
SpecificationiMac1MacBook Air2
Battery capacityNot available538 Wh
Rated charge cyclesNot available51,000 cycles17
Video playback (claimed)Not available510 h
Wireless web (claimed)Not available59 h
Included power adapterNot available1845 W
Fast chargingNot available5No fast charging.8

Connectivity

Connectivity: Apple iMac (Retina 4K, 21.5-inch, Late 2015) against Apple MacBook Air (11-inch, Early 2015)
SpecificationiMac1MacBook Air2
Wi-Fi802.11ac Wi-Fi802.11ac Wi-Fi
Bluetooth4.04.0
Ethernet10/100/1000BASE-T Gigabit Ethernet (RJ-45)No Ethernet port.8
External displays (base)11

Camera and audio

Camera and audio: Apple iMac (Retina 4K, 21.5-inch, Late 2015) against Apple MacBook Air (11-inch, Early 2015)
SpecificationiMac1MacBook Air2
CameraFaceTime HD camera720p FaceTime HD camera
SpeakersStereo speakersStereo speakers
MicrophonesDual microphonesDual microphones

Platform

Platform: Apple iMac (Retina 4K, 21.5-inch, Late 2015) against Apple MacBook Air (11-inch, Early 2015)
SpecificationiMac1MacBook Air2
Shipped withOS X El Capitan19OS X Yosemite20
Newest macOSmacOS Monterey21macOS Monterey22
Model identifieriMac16,221MacBookAir7,122
Model year20152015

Sources

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

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  2. Apple Support (UK) — MacBook Air (11-inch, Early 2015) - Technical Specifications · Default for MacBook Air · Apple’s figure · read 15 Sep 2026

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

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  4. Apple Newsroom (UK) — Apple Updates 13-inch MacBook Pro with Retina Display & MacBook Air · Apple’s figure · read 15 Sep 2026

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  5. Doesn’t apply: no battery

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

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  7. 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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  8. MacBook Air (11-inch, Early 2015): No HDMI port. No SD card slot. No Touch ID. No fast charging. No Ethernet port. Checked: Apple Support (UK) — MacBook Air (11-inch, Early 2015) - Technical Specifications. Read 9 Oct 2026

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  9. Doesn’t apply: MagSafe is a notebook charging port

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

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  11. Not published by Apple. Pages checked: Apple Support (UK) — MacBook Air (11-inch, Early 2015) - Technical Specifications; Apple Support (UK) — Identify your MacBook Air model; Apple Newsroom (UK) — Apple Updates 13-inch MacBook Pro with Retina Display & MacBook Air. Read 9 Oct 2026

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  12. 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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  13. MacBook Air (11-inch, Early 2015): Intel processor, not Apple silicon. Checked: Apple Support (UK) — MacBook Air (11-inch, Early 2015) - Technical Specifications. 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) — MacBook Pro: how to remove or install memory · Apple’s figure · read 18 Oct 2026

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

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  17. Apple Support (UK) — Determine battery cycle count for Mac laptops · Apple’s figure · read 15 Oct 2026

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  18. Doesn’t apply: internal power supply, no power adapter in the box

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

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  20. Apple Newsroom (UK) — Apple Updates 13-inch MacBook Pro with Retina Display & MacBook Air · Apple’s figure · read 9 Oct 2026

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

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  22. Apple Support (UK) — Identify your MacBook Air model · Apple’s figure · read 15 Sep 2026

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Not published by Apple

iMac. 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.

MacBook Air. Apple doesn’t publish for this Mac: colours, pixel density, brightness, refresh rate, nano-texture option, GPU cores, storage upgradeable by user. 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) — MacBook Air (11-inch, Early 2015) - Technical Specifications; Apple Support (UK) — Identify your MacBook Air model; Apple Newsroom (UK) — Apple Updates 13-inch MacBook Pro with Retina Display & MacBook Air, 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 4K, 21.5-inch, Late 2015)? · Should I upgrade my MacBook Air (11-inch, Early 2015)?

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