Quick Answer: One USB-C port has to carry charging, video and storage at the same time, so the power budget decides which hub works. A hub rated at 60 W pass-through reserves roughly 15 W for itself and its downstream ports, leaving about 45 W for the tablet. Attach Ethernet, an SSD and a card reader and the ports share a single USB 3.2 Gen 1 link at 5 Gbit/s, while HDMI runs at 18 Gbit/s in Alt Mode. Buy headroom for the ports you will add next year, not just those you use today.
A hub cannot add ports to a tablet; it can only divide the one port that exists. Every function you plug in draws from the same USB-C link, and the charging input is the only source of power. That single constraint explains almost every complaint about hubs that work on a laptop and fail on an iPad: the laptop supplies power, the tablet expects to receive it.
What one port can carry at once
A USB-C connector has four high-speed lane pairs and a configuration channel. In a hub, two pairs usually go to DisplayPort Alt Mode for video and the rest serve USB data, which is why adding a display often halves the storage throughput.
Video: Alt Mode, not a second port
HDMI 2.0 at 18 Gbit/s carries 4K at 60 Hz with 8-bit colour, the realistic ceiling for a bus-powered hub. Hubs that promise 4K at 120 Hz are using compression or asking for a stream the tablet will not send. Mirroring and extending are different features, and the tablet decides which is offered.
Data: 5 Gbit/s, shared by everyone
USB 3.2 Gen 1 gives 5 Gbit/s of signalling, around 400 Mbit/s of real throughput for a spinning drive and more for an SSD. A Gigabit Ethernet port needs about 940 Mbit/s of payload, so a file copy to a network share and a backup to a local SSD will contend.
Power delivery headroom
Pass-through wattage is quoted at the input, not at the tablet. A 60 W charger into a 60 W hub does not deliver 60 W onward: the hub’s conversion, its Ethernet PHY and any bus-powered drive take their share. Fifteen watts is a fair allowance with Ethernet and video, leaving 45 W for the tablet.
Why a hub drops the link
When the load exceeds the budget, the hub protects itself and the tablet sees a disconnect, usually as a drive spins up. The symptom is a device that vanishes from the sidebar and returns a second later. A hub with its own power input removes the fault without changing anything else.
Choosing between hub, dock and adapter
The comparison in USB-C hub vs dock comes down to where the power comes from. A dock has its own supply and can therefore offer more ports with fewer compromises; a hub borrows from the charger you already own. For a tablet used on a desk, a dock is usually the better purchase.
| Function | Interface and rate | Drawn from the port | What it competes for |
|---|
| HDMI display | HDMI 2.0, 18 Gbit/s | about 1 W | two lane pairs |
| Gigabit Ethernet | 1000BASE-T, 940 Mbit/s | 2 to 3 W | the USB 3 data lanes |
| External SSD | USB 3.2 Gen 1, 5 Gbit/s | up to 4.5 W | the same 5 Gbit/s |
| Card reader | UHS-I, 104 Mbit/s | under 1 W | very little |
| Charging input | USB PD, 60 W | reserves 15 W | the charge rate itself |
Cable choice matters as much as the hub. Many short leads sold with drives are charge-only, with no SuperSpeed pairs inside, and they negotiate 480 Mbit/s or nothing. Check that the USB-C cable for an external drive is rated for 5 Gbit/s or better, and keep it short: 1 m is plenty at a desk.
Practical scenarios
- Situation: a tablet on a desk with a 4K monitor and a wired network. Use a 100 W pass-through hub, which leaves about 60 W for the tablet after 15 W of hub overhead and a 3 W PHY.
- Situation: a photo workflow with a card reader and an SSD at once. Copy from the card to internal storage first, then back up, rather than running both across one 5 Gbit/s link.
- Situation: a hub that disconnects when a drive spins up. Move the drive to a powered hub port or fit the hub’s own 30 W supply.
- Situation: a meeting room with a fixed display. Terminate an USB-C Ethernet hub on the table and leave the video lead on a separate adapter.
FAQ
Will any USB-C hub charge an iPad?
Charging needs a hub that passes power delivery through, which most do, but the rate depends on what is attached. With nothing else plugged in, a 60 W hub will charge at close to the tablet’s own maximum. Add an SSD and Ethernet and the rate falls, because the hub takes its share first.
Why does my hub show the wrong resolution?
Usually because the hub, the cable and the display have agreed on the lowest common format. A 4K display on an HDMI 2.0 hub should run 4K at 60 Hz, but a charge-only lead in the chain or a display set to a fixed input standard will fall back to 30 Hz. Test with a known 18 Gbit/s lead.
Do I need a powered hub?
Only if you attach devices that draw real current: an SSD, a mechanical drive or a bus-powered audio interface. Keyboards and card readers are content with a passive hub. If the tablet is charging through the hub at the same time, a powered hub removes the guesswork entirely.
