Thank you for reaching out to us. I'm happy to help. I can certainly understand the confusion regarding capacity and rated energy. 

The industry standard is to advertise power banks using their "battery capacity" (e.g., 6000mAh). However, the rated energy (e.g., 3,700mAh) is a tested value that depends on the load. 

I found this article to very helpful as it explains the difference between these two measurements.

https://fansdreams.com/blogs/blog/actual-capacity-of-power-banks?srsltid=AfmBOorjZGvMFCKcsxWWs5ey8E2JmzF974S0Cn4_oE87yPMMJQNrLCxq

Please let us know if we can provide additional details.