About USB on Mac computers

USB is available with type A (USB-A) and type C (USB-C) ports, depending on the Mac model. 


USB type A ports have this shape and may also be called USB, USB 2, or USB 3 ports, depending on the USB specification supported.


USB type C ports have this shape and are available on Mac as USB 3, Thunderbolt 3, or Thunderbolt / USB 4 ports.

Learn more about identifying the ports on your Mac. If the cable from your USB device doesn't fit in the USB port on your Mac, learn about adapters you can use.

USB specifications

The specification of a USB port determines the maximum data-transfer rate (speed) and power delivered by the port. This is important primarily when you want the most speed for your USB device, or when your USB device needs more power than it's getting.

To learn which specification a USB port on your Mac supports, choose Apple menu  > About This Mac, click Support, then click Specifications. You can also use System Information to get more detail, including about USB devices directly connected to your Mac.

USB specifications on Mac Data transfer Power delivery
USB 4 Up to 40 Gbps Up to 100W at 20V
USB 3 (USB 3.1 Gen 2) Up to 10 Gbps  Up to 15W at 5V
USB 3 (USB 3.1 Gen 1) Up to 5 Gbps Up to 900 mA at 5V
Up to 480 Mbps Up to 500 mA at 5V
USB 1.1
Up to 12 Mbps Up to 500 mA at 5V

If a USB device is slow or not recognized

USB specifications all work with each other, but data-transfer speed and power are limited by the cable or device that uses the earliest specification. For example, if you connect a USB 3 device to a USB 2 port, your device is limited to USB 2 speed and power. 

  • Make sure that the USB port on your Mac and the USB cable used by your device both meet or exceed the USB specification of the device itself.
  • Plug your device directly into your Mac instead of a USB hub or other device. 
  • If your USB device came with an AC power adapter, you should probably use it. Your device might need more power than the port it's plugged into can provide.
  • Update the software on your Mac. Also check with the manufacturer of your USB device for firmware or other software updates. Then restart your Mac.

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