A standard USB 3.2 port, irrespective of the Gen n spec, is supposed to provide 5 VDC power for connected devices up to 0.9 A max. There are SOME USB ports on computers, and many on third-party hubs, etc. that ALSO offer higher current max, particularly IF the socket is specified as a CHARGING port, but that is not strictly part of the USB bus system for data devices. There are high-power CHARGERS that use the new Type C port and connector, but these are not intended as data devices.
OP, for your interest here, we should focus on use of several data devices as peripherals on a computer. For that purpose the power available from the host computer's USB 3.2 Gen n port is 5 VDC at 0.9 A max. That's NOT a lot over the older 0.5 A from USB 2.0. It IS sufficient to deal with a single "portable hard drive". There are almost NO portable hard drives able to operate on 0.5 A. In the USB 2.0 era those drives came with with their own "wall wart" power supply, or a special cable with TWO USB2 type A connectors on the end that required that they both be plugged into different host ports to get enough power. In the USB 3 era, the new drives of that type CAN operate properly on the 0.9 A max supply, so almost all of them come with NO included power supply or special cable. But NOTE that only the "laptop portable hard drives" designed to operate at lower power levels do work this way - you can NOT use a desktop HDD in an external case and expect to power that solely from a USB 3 port.
As you can expect, if you actually tried to use a small UNpowered USB 3 Hub with TWO such portable hard drives attached, there is NOT enough power for those two. So for what you want to do - attach several peripherals to one USB 3 host port via a USB 3 Hub - you REALLY should plan to get a POWERED Hub. And that can get a little confusing, so I'll expand.
A plain Hub would have ports on it only for data devices. But now one finds almost always Hubs with some standard USB 3 ports PLUS one or more "charging ports". Some charging ports are dual-function: they can operate as standard USB 3 ports, OR, if you plug in a different type of device that knows how to negotiate charging capabilities with that port, it can supply more power for the charging function. Others are DEDICATED charging ports: they do not ever function as standard USB 3 ports. So watch for the distinction.
Let's focus for now on only the standard USB 3 ports of a Hub. Each should be able to supply power at 5 VDC up to 0.9 A. So you count up the ports - say, seven of them - and calculate the max current output total is 6.3 A. That is what you need to get from the charging module that is supplied with the Hub. BUT here's the first confusion. Almost all of these systems come with charging modules that put out 12 VDC, and the Hub converts that to 5 VDC for its ports. So you have to start doing all your calculations in WATTS. Watts = Volts x Amps. So the HUB with 7 ports rated at 5 VDC, 0.9 A per port, should provide up to 7 x 5 x 0.9 = 31.5 W power to connected devices, and that is what the power "brick" must supply. It MAY be labelled in Watts. If not, take its AMP rating at 12 VDC and calculate: 12 VDC at, say, 3 A max would be 36 Watts, sufficient for that Hub load. Now here's the next factor. You almost never get an included power module with the full max Watts of the Hub it comes with. That is because it saves money, but the justification is that a user almost never uses max power on ALL connected devices simultaneously. So it is common for the max Watts of the power "brick" to be perhaps 65% to 85% of the max load for the Hub. If it's only 50%, that power module is undersized!
Next step is IF you have a Hub with Charging Ports you deal with them separately, then add. IF they are dual-function AND you plan to use those ONLY for standard data devices, then treat them as using max 0.9 A per port (4.5 W per port) and add that into the Hub max load before comparing to the power module max output. HOWEVER, IF you do plan to use such a port for actual charging of some other device (say, your phone), then check the spec for the max current that port can put out (might be 1.5 or 2.5 A), calculate the Watts, and use that. IF you have a DEDICATED charging port you will NOT use, ignore it; if you plan to USE it for charging, calculate its max power and add that in. NOW you know the max power the Hub must be prepared to supply, and can compare that to the max power its included "brick" can offer. MAYBE add a little to the Hub max to allow for a small inefficiency in power conversion from 12 V to 5 V.
Hint: sometimes you are better to buy a Hub with more ports than you need, just so you get a unit that comes with a larger power "brick" capacity.
NOTE this, although you did not mention it as part of the power inquiry. I have seen lots of USB 3 Powered Hubs that are NOT clear on what Gen n spec they meet. Remember that today they all are supposed to be called USB 3.2 Gen n, but many sellers have used older descriptions. For DATA TRANSFER, the Gen 1 spec is 5 Gb/s max; for Gen 2 it is 10 Mb/s; Gen 2x2 is 20 Mb/s. MANY do not make any statement, and often just say "USB 3" OR "USB 3.0", so you should expect those to be Gen 1 only. I have seen some models that do specify Gen 2, so they should be good up to 10 Mb/s. I have seen NONE claiming USB 3.2 Gen 2x2.
Right now, there are few devices that actually can move data over 5 Gb/s, but faster ones will show up in the future, and you are trying to plan for that. More importantly, that speed is the max speed of the single connection between the Hub and the host computer's USB 3.2 Gen n port. So that max rate is shared by ALL of the connected and active devices on the Hub. It would be wise to get the max speed you can for the Hub (currently, Gen 2 at 10 Mb/s, I believe) AND ensure that you use the correct cable with Type C connectors to make the connections, AND that you connect to a USB 3.2 Gen 2 port on the computer that has a Type C socket.
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