The wattage on the box is a budget, not a promise

This is the number that starts the most arguments at a phone counter, so it gets the first page on this site. When a car charger says 99W and lists six outputs, 99W is the size of the pie. It is not the size of anyone's slice. Plug in one phone and the unit will still only offer what that phone negotiates for, and no figure on the box tells you what that negotiation lands on.

The reason manufacturers quote a total is that a total is the only figure that is true regardless of what you plug in. A per-port figure depends on which port, what else is connected, and which protocol the device speaks. A total sidesteps all of that. It is not dishonest, exactly. It just answers a question nobody asked.

You can spot the difference in the listings themselves. Some publish a breakdown: 90W total with dual 45W USB-C stated, or 52.5W total with 30W named on one output. Those are useful sentences, because they tell you what one device can expect. Others state a total across five or six outputs and stop, and there is no honest way to reason about what a single port will do from that alone.

It gets stranger when you add the numbers up. A 25000 mAh bank in this catalog states 165W total output with three USB-C ports at 100W maximum each. Three hundred watts of stated port maximums against a 165W total. Both figures are accurate; they simply describe different situations. Any one port can reach 100W when the others are idle. All three cannot.

The practical rule is short. If a listing names a wattage next to a specific port, treat it as what that port can do on its own. If a listing names a wattage next to a port count, treat it as a ceiling for the whole unit and assume the split is not published, because it usually is not.