Capacity is the battery's fuel tank

Think of capacity as the size of the battery's fuel tank. It tells you exactly how much energy the unit can hold. For example, a 1024 Wh power station can run a 10 W device for roughly 100 hours, or a 100 W appliance for about 10 hours, before the internal inverter shuts things down.

Plan for real-world usable capacity

In the real world, you will not get 100% of the capacity printed on the box. As the station converts its internal DC battery power into the AC power your electronics need, it naturally loses some energy. Because of these conversion losses, expect the usable capacity to be about 15% to 20% lower than advertised. A good rule of thumb is to plan on having 80% to 85% of the rated Wh available when calculating your setup.