The only two power banks worth carrying

Capacity printed on a power bank is cell capacity, not delivered capacity. Conversion losses mean a 10,000mAh pack hands over roughly 6,500mAh in practice, and the gap widens on cheaper units.

What we measured

Delivered milliamp-hours at the port, not the number on the case. Self-discharge over four weeks sitting in a drawer. And weight, because a power bank you leave at home has a capacity of zero.

The weight threshold

Above about 250 grams, people stop carrying them. That single fact eliminates most of what is sold, including several packs with excellent numbers.

Why two and not five

The rest were either heavier than their delivered capacity justified, or lost meaningful charge just sitting unused. Both failures make a power bank an object you own rather than a tool you use.