USB-C and Power Delivery Explained — One Cable, Many Speeds

USB-C is one connector, but power and data capabilities vary widely. Here’s how to read the specs and choose the right cables and adapters.

Connector vs. Protocol

USB-C is the physical connector. What it does depends on the device and cable: USB 2.0, USB 3.x, USB4, Thunderbolt 3/4, and Power Delivery are separate specs. A cable can support only power, only data, or both — and at different levels.

Power Delivery (PD) Basics

PD negotiates voltage and current between source and device. Common levels: 18 W (phones), 45–65 W (laptops), 100 W (high-power laptops and docks). Your charger and cable must support the wattage your device can take; otherwise you get slower charging or no PD at all.

Data Speeds — USB 3.2 and USB4

USB 3.2 Gen 1 is 5 Gbps; Gen 2 is 10 Gbps. USB4 starts at 20 Gbps and can go to 40 Gbps with Thunderbolt. For most users, 10 Gbps is plenty; 40 Gbps matters for multiple 4K displays or fast storage. Cable length and quality affect achievable speed.

Cable and Adapter Pitfalls

Cheap cables often do power only or USB 2.0 data. For PD above 60 W or USB4/Thunderbolt, use certified cables. Length matters: passive cables over ~2 m may drop to lower speeds. Active cables preserve signal over longer runs but cost more.

Building a Minimal Setup

One 65 W (or higher) PD charger can power a laptop and phone. Add a USB-C hub or dock if you need HDMI, Ethernet, and USB-A. Match the hub’s power passthrough to your laptop’s requirement so it charges under load.