What Can a USB-C Hub Do for Your Laptop, and Where Does It Fall Short?
Summary
A USB-C hub turns one USB-C port into several, commonly USB-A, HDMI, a card reader and a charging input. What each of those ports can actually do is set by three things: the port on your laptop, the chip in the hub and the fine print on the hub's spec page. Reading one hub's spec page line by line shows where the limits usually hide.
One hub, line by line
Lemorele's TC38L is an 8-in-1 hub, and its product page lists these ports, and the right column is the part that's easy to miss.
| Port on the TC38L | What the spec page adds |
|---|---|
| HDMI 1.4 | "Supports up to 4K@30Hz resolution; supports both mirror and extended display modes" |
| Three USB-A 3.0 | "Max transfer speed up to 5Gbps," with device charging "total 5V/3A, max 1.2A per port" |
| USB-C data port | "Data transfer only; does not support power delivery or HDMI output" |
| USB-C PD port | "Supports fast charging up to 100W; charging only, no data or video transmission" |
| SD and microSD slots | "USB 2.0 speed (480Mbps theoretical, actual 20–30MB/s)" |
Two of the USB-C ports look the same and do opposite jobs, one for data and one for power. The card slots run at USB 2.0 speed even though the USB-A ports next to them are rated at 5Gbps. And the three USB-A ports share one charging budget of 3A between them.
Video depends on your laptop's port
An HDMI socket on a hub does nothing unless the laptop sends video down the USB-C cable. Lemorele lists the TC38L as not compatible with "USB-C to HDMI output via data-only ports," which means laptop ports that carry data but not video. The DisplayPort FAQ describes the result on such a port: "No video data will be received by the display, so there will be no image on the screen."
The laptop's documentation is where to find out. The DisplayPort FAQ says ports that carry video "will normally include the DisplayPort (DP) logo near the connector," and a Thunderbolt symbol next to the port is another sign. Our guide to hubs with HDMI and charging goes into the refresh rate and the charging figures in more detail.
Speed is shared
Everything on the hub reaches the laptop through one cable, so the hub's ports are sharing whatever that connection carries. USB-IF's guidelines add that the host, the device and the cable "must all offer USB 3.2 or USB4® capabilities" for USB 3.2 or USB4 speed, and that a USB 2.0 product or cable in the chain "will perform at the slower USB 2.0 speed."
So a hub won't make a 5Gbps laptop port faster. It won't raise the number of screens your laptop supports either, which Apple states outright for its Macs: a hub "does not increase the maximum number of displays that you can connect."
Browsing for one? Browse docks and hubs in the feed →
Sources
- Lemorele, TC38L USB-C 8-in-1 Hub
- DisplayPort (VESA), FAQ
- USB-IF, USB Type-C and USB 2.0 Type-C Cable and Connector Language Usage Guidelines
- Apple, How many displays can be connected to MacBook Air
We have not tested these products. Specs and guidance are as published on these pages on the date above and can change; the manufacturer's page for your model has the current details.