How do I test my USB-C or Thunderbolt port speed online?

Connect a USB device to your Type-C port and click 'Scan USB-C Device'. If supported, the WebUSB API will query the device's speed indicators, descriptor versions, and vendor attributes to verify port specifications.

What is USB-C Alternate Mode (Alt-Mode)?

Alternate Mode allows a physical USB-C port to carry non-USB signals, such as DisplayPort or HDMI video data and PCIe lanes, enabling a single cable connection to support 4K displays and external GPU enclosures.

What is USB Power Delivery (USB-PD) and how many watts can it carry?

USB Power Delivery is a protocol enabling dynamic voltage negotiation up to 100W under standard rules, and up to 240W (Extended Power Range - EPR) in newer USB-C specifications to power high-draw laptops.

What is the difference between USB4 and Thunderbolt 4?

Thunderbolt 4 mandates strict hardware configurations, requiring dual 4K monitor support, 40 Gbps bandwidth, and PCIe data tunneling, whereas USB4 specifications make some of these features optional for manufacturers.

USB-C & Thunderbolt Speed Profiler Type-C Protocol Suite

Analyze physical link bandwidth, scan connected USB-C peripherals, simulate Power Delivery profiles, and evaluate display lane allocations.

TYPE-C PORTS ACTIVE

1. Interactive Connection Simulator Sandbox

PORT CONFIGURATION: DISCONNECTED

Configure alternate mode variables below to update port status.

Cable Protocol

Power Profile

Alternate Display

2. WebUSB Accessory Device Scanner

📋 No Authorized Port Accessories Found

Connect accessories to your port, click scan, and authorize the browser to query device IDs.

3. Active Link State Telemetry

Max Port Speed 5 Gbps

Charging Profile 15W

Thermal Profile Cool (Nominal)

Display Lanes 0 active video lanes

Active Channel Pin Allocations

Pins A1-A12 (TX1/RX1 CC Data)

4. Browser WebUSB Compatibility

WebUSB Interface: Scanning...

System Driver Sandbox: SANDBOXED ACTIVE

5. Port Profile Exporter

Export the simulated configuration profile, selected Power Delivery profiles, and WebUSB devices parameters to a local file.

📚 Technical Diagnostic Guide

USB-C vs Thunderbolt: Guide to Bandwidths, Power Delivery, Alt-Modes & Lanes

The USB Type-C physical connector is a universal standard, but the underlying protocols define its capabilities. A single USB-C port might only carry USB 2.0 speeds (480 Mbps) on a budget phone, while a matching port on a professional notebook might support **Thunderbolt 4** or **USB4** speeds (40 to 80 Gbps).

⚡ Bandwidths and Protocol Speeds (5Gbps to 80Gbps)

The interface version determines data capacities. Standard **USB 3.2 Gen 1** provides 5 Gbps, **Gen 2** provides 10 Gbps, and dual-lane **Gen 2x2** reaches 20 Gbps. High-performance **Thunderbolt 3**, **Thunderbolt 4**, and **USB4** integrate PCIe data tunneling to achieve 40 Gbps, whereas newer **USB4 V2** standards deliver up to 80 Gbps symmetric bandwidth over copper wire interfaces.

🔌 Power Delivery Negotiation (USB-PD & EPR)

USB Power Delivery allows connected devices to negotiate voltage profiles dynamically. Older profiles maxed out at 100W (20V @ 5A). The newer **Extended Power Range (EPR)** standard permits voltage steps up to 48V at 5A, allowing compatible USB-C cables to supply up to 240W of power to high-performance gaming laptops.

📺 DisplayPort Alt-Mode and Active Lane Allocation

A USB Type-C connector features 4 high-speed differential signal lanes. Under DisplayPort Alternate Mode, the system can allocate lanes dynamically. For instance, it can assign 2 lanes to carry 4K video data, leaving the remaining 2 lanes for standard USB 3.2 data. Alternatively, it can dedicate all 4 lanes to video to support dual 4K or single 8K displays.

❓ Frequently Asked Questions