iMac external features, ports, and connectors

Learn about the external features, ports, and connectors on iMac computers from late 2012 and later (including Retina 4K and Retina 5K models).

Front view

  1. FaceTime HD Camera
  2. Dual mics
  3. Ambient light sensor
  4. Built-in Wi-Fi and Bluetooth
  5. Built-in stereo speakers

Rear I/O panel

All ports and connectors described in this document are located on the Input/Output (I/O) panel. This panel is located at the bottom-right on the back of the computer:

  1. 3.5mm headphone jack
  2. SD (Secure Digital) Card slot
  3. Four USB 3.0 ports
  4. Two Thunderbolt or Thunderbolt 2 ports
  5. Ethernet port

External features


Dual microphones

The dual microphones operate independently from all other audio input ports and are always available. The built-in microphones support recording at bit depths of 16, 20, or 24 bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz. Audio recorded from the microphone is presented as a stereo data stream with the same data on both the left and right channels. You can adjust the microphone gain from -16 dB to +30 dB.

Dual microphones enable beam-forming technology, which delivers more accuracy when using Dictation and reduces background noise for FaceTime video calls.

Built-in FaceTime HD camera

You can use the FaceTime HD camera to video chat with FaceTime for Mac or iChat over a broadband connection, take pictures using Photo Booth, or capture video through iMovie. The camera has an indicator light that turns on when the camera is in use.

Kensington lock slot

A security lock slot is on the back of the iMac below the power cord receptacle.

I/O ports


1. 3.5mm headphone jack


Line/headphone output

The headphone output is automatically selected for audio output if no external S/PDIF optical digital output device is detected. The headphone output supports a stereo data stream at bit depths of 16, 20, or 24 bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz. The headphone output volume can be adjusted from 0.0 dB to -43.0 dB.

During playback of a 1 kHz sine wave at -3 dBFS voltage level, 24-bit sample depth, 44.1 kHz output sample rate, 100 k load (unless otherwise specified), the audio output has the following nominal specifications:

  • Jack type: 3.5 mm (1/8-inch) stereo combo
  • Maximum output voltage: 1.4 VRMS (+5.15 dBu)
  • Output impedance: <24 ohms
  • Frequency response: 20 Hz to 20 kHz, +0.5 dB/-3 dB
  • Signal-to-noise ratio (SNR): >90 dB
  • Total harmonic distortion + noise (THD+N): <-80 dB (0.007%)
  • Channel separation: >85 dB

S/PDIF optical digital output

The S/PDIF (Sony/Philips Digital Interface Format) optical digital output is automatically selected when an S/PDIF optical digital output device is detected on the external combination audio port. The S/PDIF optical digital output supports pulse-code modulation (PCM) and Arc Consistency Algorithm #3 (AC-3) audio formats with the following stereo data stream characteristics:

  • PCM: 16, 20, or 24 bits per sample at sample rates of 44.1 kHz, 48 kHz, or 96 kHz
  • AC-3: 16 bits per sample at sample rates of 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz

The S/PDIF optical output channel status conforms to International Electrotechnical Commission (IEC) 60958-3 consumer mode digital audio.

During playback of a 1 kHz sine wave (S/PDIF output format at 0 dBFS output level, 44.1 kHz sample rate, 24-bit sample depth, unless otherwise specified), the digital audio output has the following nominal specifications:

  • Jack type: 3.5 mm (1/8-inch) stereo combo
  • Digital audio signal-to-noise ratio (SNR): >130 dB
  • Digital audio total harmonic distortion + noise (THD+N): <-130 dB (0.00003%)

2. Built-in SDXC (Secure Digital Extended Capacity) card reader

The built-in SDXC card slot allows your iMac (Late 2012 and later) to read and write data to SD media. The slot accepts cards that are Standard SD (Secure Digital) 4 MB to 4 GB, SDHC (Secure Digital High Capacity) 4 GB to 32 GB, and SDXC (Secure Digital Extended Capacity) cards of 32 GB and larger. For complete information on the card slot, see About the SD and SDXC card slot.

3. Four USB (Universal Serial Bus) 3.0 ports

The back of the iMac (Late 2012 and later) has a total of four USB 3.0 compliant ports. You can connect compliant USB 3.0, USB 2.0, and USB 1.1 devices to these ports. See Using USB 3 devices on Mac computers FAQ for more details.

4. Thunderbolt ports

Thunderbolt is a revolutionary I/O technology that supports high-resolution displays and high-performance data devices through a single, compact port.

Thunderbolt digital video output

iMac (Late 2012 through Mid 2014) computers have two Thunderbolt ports.

The following iMac computers have two Thunderbolt 2 ports:

  • iMac (21.5-inch, Late 2015)
  • iMac (Retina 4K, 21.5-inch, Late 2015)
  • iMac (Retina 5K, 27-inch, Late 2015)
  • iMac (Retina 5K, 27-inch, Mid 2015)
  • iMac (Retina 5K, 27-inch, Late 2014)

Thunderbolt and Thunderbolt 2 ports support:

  • Mini DisplayPort output using a Mini DisplayPort to Mini DisplayPort cable (optional)
  • DVI output using a Mini DisplayPort to DVI Adapter (optional)
  • VGA output using a Mini DisplayPort to VGA Adapter (optional)
  • Dual-Link DVI output using Mini DisplayPort to Dual-Link DVI Adapter. Supports 30-inch Apple Cinema HD Display (optional)
  • HDMI audio and video output using a third-party Mini DisplayPort to HDMI Adapter
  • Target Display Mode: In this mode, some iMac systems can serve as a display for another Mac. This is supported via the Thunderbolt port using a Thunderbolt to Thunderbolt cable (not supported via a Mini DisplayPort cable).
    Note: iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can't be used as Target Display Mode displays.

5. Ethernet port (10/100/1000 Base-T)

iMac (Late 2012 and later) computers have a built-in Ethernet port for 10Base-T/UTP, 100Base-TX, and 1000Base-T Gigabit operation. You can connect your iMac to an Ethernet cable from a cable or DSL modem, hub, switch, or router, or to another Mac computer.

The connected device can be either a 10Base-T, 100Base-T, or 1000Base-T device. The port automatically detects which type of device you connect. You don't need to use an Ethernet crossover cable to connect to other Ethernet devices.

The Ethernet port supports the configuration of Ethernet frames larger than 1,500 MTU (Maximum Transmission Unit).

FaceTime is not available in all countries or regions.

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