Buy a powered hub — the Plugable 7-port with its 36W adapteris the default — if anything you plug in has a motor, a screen, a heater or a radio: external hard drives, bus-powered SSDs, 4K webcams, audio interfaces, or a phone you want to charge at a useful rate. Buy an unpowered (bus-powered) hub if you are adding keyboards, mice, dongles, flash drives and wired headsets. That is the whole decision, and it comes down to one published number.
A USB 3.0 host port supplies 900 milliamps at 5 volts— about 4.5 watts — and USB 2.0 supplies 500mA. A bus-powered hub has no supply of its own, so it takes that single port’s budget, keeps a little for its own controller, and divides the rest between everything downstream. Four devices on a bus-powered hub are sharing one port’s worth of current. A self-powered hub brings its own adapter and gives each port the full spec allowance, which is why the Plugable can hand 1.5A to two of its ports for charging while the other five run at 900mA each.
The symptoms of an underpowered hub
This is worth knowing because the failure does not announce itself as a power problem. What you see instead:
- A device disconnects and reconnects in a loop, often with the Windows connection chime every few seconds.
- An external drive spins up, clicks and drops off under load, or copies fail part way through a large transfer.
- A webcam works at 720p and fails at 4K, because the higher mode draws more current.
- A microphone or audio interface pops or cuts out when something else on the hub wakes up.
- Phones charge at a trickle, or show “slow charger”, because the port is handing out a fraction of an amp.
If that list looks familiar, read the hub troubleshooting guide before you buy anything — Windows selective suspend and a short, poor-quality host cable cause the same symptoms, and both are free to rule out.
The arithmetic, device by device
Published current draws vary by model, so treat these as the orders of magnitude they are, not as specifications:
- Keyboard, mouse, wireless receiver: tens of milliamps each. A bus-powered hub runs several of these without noticing.
- Flash drive, wired headset: around 100mA. Still fine.
- Portable SSD, 4K webcam, USB microphone: several hundred milliamps. One is usually fine; two on a bus-powered hub is where it starts misbehaving.
- Bus-powered 2.5-inch hard drive:most of a port’s budget on its own, and it spikes at spin-up.
- 3.5-inch desktop drive, DAC and amplifier, phone charging: more than a host port can supply. These need a powered hub, full stop.
The simple test: add up how many of your devices came with their own power brick in the box, then look at how many of the rest you would describe as “doing something physical”. If the answer is more than one, buy powered.
Powered does not mean faster
A hub does not multiply bandwidth. Every port on a USB 3.0 hub shares the one 5Gbps upstream link, whether the hub has a power adapter or not — so two drives copying at once will halve, regardless. Power fixes stability; it does nothing for throughput.
If bandwidth is the problem rather than power, the answer is a different class of device: a dock with its own controller, or a Thunderbolt dock with 40Gbps upstream. The distinction is covered in USB hub vs docking station and USB-C vs Thunderbolt dock.
The third category nobody explains: PD pass-through
Some USB-C hubs are neither. They have no wall adapter of their own, but they accept a USB-C power input and pass most of it through to your laptop while keeping a slice for themselves — the Anker 8-in-1 below takes up to 100W in and uses roughly 15W. That is a genuinely good arrangement for a laptop desk: one cable to the laptop carries data, video and charge.
What it is not is a substitute for a self-powered hub on a desktop. If nothing is feeding the hub’s USB-C input, it is running on bus power like any other unpowered hub, and the arithmetic above applies.
Which to buy
| Hub type | Power source | Right for |
|---|
| Self-powered (powered) | Its own 24W to 36W adapter | Drives, webcams, audio gear, charging, 5+ devices |
| Bus-powered (unpowered) | The host port's 900mA, shared | Keyboards, mice, dongles, flash drives, travel |
| USB-C with PD pass-through | A charger upstream, shared with the laptop | A one-cable laptop desk with video |
| Dock | Always its own supply | Multiple monitors, ethernet, and charging together |
One more practical note: on a powered hub, check whether the adapter is external or integrated, and whether it is a barrel jack or USB-C. An external brick is one more thing to find a socket for, which is an argument for a desk-edge power strip rather than against the hub.
