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Check USB Speed on Mac: Full Guide

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Check USB Speed on Mac: Full Guide

To check the USB speed on your Mac, open System Information (hold Option and click the Apple menu, then select System Information) and go to USB under Hardware. Select your device to see its link speed, such as 5 Gb/s for USB 3.0 or 40 Gb/s for Thunderbolt 3. This article explains how to interpret that number, how to test real-world throughput, and what to do if speeds seem slower than expected.

How USB Speed Is Determined on a Mac

USB speed depends on the weakest link in the chain: the port on your Mac, the cable, and the device itself. Each generation has a theoretical maximum, but real-world performance is lower due to protocol overhead and other factors.

  • USB 2.0: 480 Mb/s (about 60 MB/s theoretical)
  • USB 3.0 / 3.1 Gen 1: 5 Gb/s (about 625 MB/s theoretical)
  • USB 3.1 Gen 2 / USB 3.2 Gen 2: 10 Gb/s (about 1.25 GB/s theoretical)
  • USB 3.2 Gen 2×2: 20 Gb/s (about 2.5 GB/s theoretical)
  • USB4 / Thunderbolt 3/4: 40 Gb/s (about 5 GB/s theoretical)

Thunderbolt ports are backward-compatible with USB, but they only run at USB speeds when connected to a USB device. Similarly, a USB-C port on a Mac may support USB 3.1 Gen 2 or Thunderbolt, depending on the model.

How to Check USB Speed in System Information

macOS reports the negotiated link speed for each USB device. Here’s how to find it:

  1. Connect the USB device to your Mac.
  2. Hold the Option key and click the Apple menu (top-left).
  3. Select System Information (not About This Mac).
  4. In the sidebar, under Hardware, click USB.
  5. Select your device from the list. Look for Speed: (e.g., “Up to 5 Gb/s�).

If you don’t see the device, try a different port or cable. Some hubs or docks may report the hub’s speed rather than the device’s.

Using Terminal to See USB Speed

For a more detailed view, you can use the system_profiler command in Terminal:

  1. Open Terminal (in /Applications/Utilities).
  2. Type system_profiler SPUSBDataType and press Return.
  3. Scroll through the output to find your device. The “Speed� line shows the negotiated link speed.

This method shows the same information as System Information but in a text format that’s easy to copy or search.

How to Test Real-World USB Speed

The link speed in System Information is the theoretical maximum. To see actual read/write speeds, you need a benchmark tool or a simple file transfer test.

  • Use a benchmarking app like AmorphousDiskMark or Blackmagic Disk Speed Test (available on the Mac App Store). These write and read test files to measure throughput.
  • Copy a large file (e.g., 5–10 GB) from your internal drive to the USB device and time it. Divide the file size by the time in seconds to get MB/s.
  • Use the dd command in Terminal for a quick test, but be careful to point it to the correct drive to avoid data loss.

Real-world speeds are typically 70–85% of the theoretical maximum. For example, a USB 3.0 drive might show 5 Gb/s in System Information but only transfer at 400–450 MB/s.

Why Your USB Speed Might Be Slow

If your actual transfer speeds are much lower than expected, check these common causes:

  • Using a USB 2.0 cable with a USB 3.0 device. The cable limits the speed.
  • Plugging into the wrong port – some Macs have USB 2.0 ports (older models) or only certain ports support Thunderbolt.
  • Device limitations – many flash drives are slower than the port allows, especially small or budget models.
  • File system overhead – formatting (e.g., exFAT vs APFS) can affect speed.
  • Background tasks – Spotlight indexing or Time Machine backups can slow transfers.

Also note that USB hubs (especially unpowered ones) can reduce speed because they share bandwidth among connected devices.

USB-C and Thunderbolt: What’s the Difference?

USB-C is a connector shape, not a speed standard. Thunderbolt 3/4 uses the USB-C connector but supports up to 40 Gb/s, along with PCIe and DisplayPort signals. Many Macs have Thunderbolt ports that also support USB 3.1 Gen 2 (10 Gb/s) when used with USB devices.

To check if your Mac has Thunderbolt, look for a lightning bolt icon next to the port, or check the tech specs for your model. Even if a port is Thunderbolt, it will only run at USB speeds when a USB device is connected.

Frequently Asked Questions

How do I know if my USB port is USB 3.0 on a Mac?

Open System Information > USB, and look at the “Speed� for a device. If it says “Up to 5 Gb/s� or higher, the port is USB 3.0 or better. Older Macs with USB-A ports may only support USB 2.0 (480 Mb/s). You can also check your Mac’s tech specs online.

Why does my USB 3.0 drive only show 480 Mb/s?

This usually means the drive is connected through a USB 2.0 cable or hub, or the drive itself is USB 2.0. Try a different cable, plug directly into the Mac, and check the drive’s specifications.

Can I increase USB speed on my Mac?

No, the hardware determines the maximum speed. But you can ensure you’re using a high-quality cable that supports the same USB version, avoid hubs, and use a drive with faster NAND (if it’s an SSD). Updating macOS may also improve compatibility.

Is Thunderbolt faster than USB on Mac?

Yes, Thunderbolt 3/4 supports up to 40 Gb/s, while USB 3.1 Gen 2 is 10 Gb/s. However, you need a Thunderbolt device and cable to get those speeds. A USB device will only run at USB speeds even in a Thunderbolt port.

How do I check the speed of a USB-C flash drive?

Connect it, go to System Information > USB, and look at the Speed field. For real-world speed, use a benchmark app or copy a large file and time it. Note that many USB-C flash drives are USB 3.0 (5 Gb/s) or USB 3.1 Gen 1, not necessarily faster than USB-A versions.

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Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.