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Inferred From Behavior, Not Read From Hardware

USB Bandwidth & Port Speed Analyzer

No browser API reports your USB port's actual link speed, and WebUSB cannot fill that gap either — a camera actively streaming is normally claimed by the OS, blocking simultaneous WebUSB access. This instead negotiates progressively higher resolution/frame-rate combinations and observes what your camera actually delivers, clearly labelled as an inference rather than a hardware readout.

Live

Camera off

Select a device and click Run Test. This steps through several resolution/frame-rate combinations automatically.

Result

RequestedAchievedMet

Verdict: —

—

Notes

Why bandwidth ceilings show up this way

Uncompressed or lightly-compressed high-resolution, high-frame-rate video needs substantial sustained USB throughput — 4K at 30fps sits well beyond what USB 2.0's shared ~480Mbps bus comfortably provides alongside other connected devices. When a camera silently falls back to a lower resolution or frame rate than requested, that pattern is consistent with hitting exactly this kind of ceiling, even though this tool cannot read the port specification directly.

Fixing a suspected bandwidth ceiling

Move to a different portTry a USB 3.0/3.1 port directly on your computer — often color-coded blue inside the connector, though check your OS device manager to be certain.
Remove hubsUnpowered hubs and hubs shared with other high-bandwidth devices are common, easily-missed culprits.
Check the cableA USB 2.0-spec cable will bottleneck a USB 3.0 port and device regardless of what either end supports.

Benchmark Reference

Verdict Thresholds at a Glance

GradeModes met (of 4)What it means
No ceiling observed4 of 4Delivered every tested mode up to 4K30 — consistent with USB 3.0/3.1.
Fine for calls2 – 3 of 4Reliable up to 1080p — covers essentially all conferencing use.
Possible ceiling0 – 1 of 4Struggled beyond 720p/basic 1080p — check the port and cable.

The four tested modes are 720p30, 1080p30, 1080p60, and 4K30 — this tool's own real negotiation results, not an estimate.

Step-by-Step

How to Run the Test

  1. Select your device from the dropdown.
  2. Click "Run Test" and allow camera access when prompted.
  3. Let it step through each resolution/frame-rate combination automatically — this takes a few seconds per mode.
  4. Read your verdict and check the device name note for any explicit USB generation mentioned.

Common Questions

Frequently Asked Questions

Does this read my USB port's actual speed?
No — no getUserMedia API reports USB link speed, and WebUSB cannot reliably help either, since a camera actively streaming video is normally claimed by the OS's own camera stack, blocking simultaneous WebUSB access. This infers a likely bandwidth ceiling from what resolution/frame-rate combinations the camera actually delivers versus what was requested.
My camera is rated for 4K but only delivers 1080p — is it broken?
Possibly not broken at all — check which port it is plugged into first. A USB 2.0 port or an unpowered hub is a very common, easily fixed cause, and moving to a USB 3.0/3.1 port directly on your computer often resolves it immediately.
How do I know if my port is USB 2.0 or 3.0?
Physically, USB 3.0 ports are very often color-coded blue inside the connector on many computers, though this is a convention, not a guarantee. Your OS's device manager (Windows) or System Report (Mac) will state the actual generation definitively for any connected device.
Why does the test briefly interrupt my camera preview?
Each resolution/frame-rate combination requires reopening the device with different constraints, which briefly stops and restarts the stream — this is expected and the same reason similar probing tools on this site behave the same way.
Does this apply to microphones too?
No — this tests video bandwidth specifically, since USB video at high resolution and frame rate is what actually strains USB 2.0-class bandwidth. Microphone audio needs a small fraction of that throughput regardless of USB generation.